The WordPress Customiser is the live-preview editor that underpins classic-theme customisation. For the decade before block themes arrived, it was the main visual tool every WordPress user learned. It still powers tens of millions of WordPress sites worldwide and remains the primary customisation interface for anyone running Astra, GeneratePress, OceanWP, or any other classic theme. This guide covers what the Customiser is, how to open it, every panel it provides, the Site Identity settings to configure first, how to add safe custom CSS, scheduling changes for a future date, and how it compares to the newer Full Site Editor.
What the Customiser is · How to open the Customiser · Customiser panels explained · Setting up Site Identity · Adding custom CSS · Scheduling changes for a future date · Customiser vs Full Site Editor · Troubleshooting common issues · Advanced: theme-specific panels and plugin extensions · Frequently asked questions
The WordPress Customiser is a built-in visual tool for personalising the appearance of your site. It covers:
Every change is shown in a live preview before publishing. You can experiment freely and only apply what you like.
Important: the Customiser is only available on classic themes. Block themes (Twenty Twenty-Five and similar) use the Full Site Editor instead.
Two paths.
Appearance > Customize.
While viewing your site as an administrator, click Customize in the admin toolbar at the top of the page. Jumps straight into the Customiser for the page you were viewing.
The screen splits into two regions: the settings sidebar on the left; a live preview of the site on the right. Changes in the sidebar update the preview instantly.
Standard panels on most classic themes (theme developers can add more):
Logo, site title, tagline, site icon (favicon). The foundational branding panel.
Background, accent, text colours. Options vary dramatically by theme — some themes offer just a single background colour, others expose a full palette of ten customisable elements.
Upload or pick a wide image to display at the top of the site. Used by classic themes as a banner or hero area. Not all themes include this panel.
Full-page background behind content. Position, repeat, scroll attachment options.
Create navigation menus, assign to theme locations (Primary, Footer, Social, Sidebar). Drag-and-drop reordering. Add pages, posts, categories, tags, custom links. See our menu guide.
Add, remove and rearrange widgets in sidebar and footer areas. In WordPress 5.8+ the Customiser's Widgets panel also shows the block-based widget editor.
Latest posts or static page. If static, pick the Homepage and Posts page. See the homepage setup guide.
Custom CSS editor with syntax highlighting. Rules apply on top of the theme's default styles.
Premium classic themes often add panels for Header Layout, Footer Layout, Typography, Blog Settings, WooCommerce options. Astra Pro, Kadence and OceanWP all add substantial custom panels.
Almost always the first panel to configure after installing a new theme.
Click Select logo. Upload PNG (with transparency) or SVG. WordPress may ask you to crop; skip if the image is already correctly sized. Typical header logos display at 200–400 px wide; upload at 2x (400–800 px wide) for sharp rendering on high-DPI displays.
Your business or website name. Displayed in the header (unless hidden by the theme when a logo is present) and used by search engines if no SEO plugin overrides.
Short description: "Accountants for UK freelancers", "Independent bookshop in Hay-on-Wye", "Children's charity in Liverpool". Theme-dependent whether displayed visibly; always read by screen readers.
Upload a square image, minimum 512 × 512 px. WordPress automatically generates all the smaller sizes needed for browser tabs, bookmarks, iPhone home-screen icons, Android app launchers.
Click Publish at the top of the sidebar to save.
The Additional CSS panel is the safest place for small visual tweaks that the theme's built-in options do not expose. Changes are stored in the database, not in theme files — theme updates do not overwrite them.
Increasing the site title font size:
.site-title { font-size: 2.5rem; }Hiding the WordPress admin bar on the front end:
#wpadminbar { display: none; }Changing link colour site-wide:
a { color: #00695c; }
a:hover { color: #004d40; }Use browser DevTools. Right-click the element you want to change, choose Inspect. DevTools highlights the HTML and shows the CSS selectors. Copy the selector; paste into Additional CSS; write your new rule.
Custom CSS is theme-specific. Switching to a different theme abandons the CSS. If you revert to the original theme, CSS reappears. Always keep a copy of important CSS in a separate text file or password-manager note for reference.
For extensive modifications (dozens of rules, template changes, function additions), a child theme is the proper home. Additional CSS is ideal for 1–20 rules.
A lesser-known Customiser feature: schedule changes for a future go-live time.
WordPress applies the changes automatically at the scheduled time. Useful for:
You can return to the Customiser before the scheduled time to modify or cancel the scheduled change.
| Aspect | Customiser | Full Site Editor |
|---|---|---|
| Available on | Classic themes | Block themes |
| Editing model | Panel-based settings | Block-based visual editing |
| Header / footer | Limited; theme-dependent | Full visual control |
| Templates | PHP template files | Edit visually |
| Global styles | Theme-dependent + Additional CSS | Unified Styles panel |
| Scheduled publishing | Yes | No native support |
| Learning curve | Lower initially | Moderate, consistent with Block Editor |
For new sites in 2026, a block theme with FSE is the more powerful and future-proof choice. The Customiser remains capable for existing classic-theme sites.
You clicked Publish but the site still shows old version — clear caches. LiteSpeed Cache (Toolbox > Purge All), browser (Ctrl+F5), CDN (Cloudflare purge if applicable).
Usually caused by a plugin conflict. Deactivate plugins one at a time, reload the Customiser, find the culprit. Often a security plugin overly restrictive about iframes (the Customiser uses an iframe for the preview).
You are on a block theme. Block themes do not include the Customiser — use Full Site Editor at Appearance > Editor.
Sometimes caused by incorrect database permissions. Check with your host. Less commonly, a plugin overrides Customiser settings.
Browser cache or the CSS specificity is insufficient. Use DevTools to confirm your rule is loaded; if loaded but overridden, add !important sparingly or use a more specific selector.
Premium classic themes extend the Customiser substantially. Astra adds Header Builder, Footer Builder, WooCommerce Settings, Typography. Kadence classic adds a similar suite. OceanWP adds dozens of layout controls.
When customising a premium theme, dig into its unique panels first — they typically expose more options than the standard WordPress panels.
Some plugins register Customiser panels:
Keep an eye on your Customiser after installing new plugins — some add controls that are easy to miss.
Why do I not see the Customiser in my dashboard?
Your theme is a block theme. Block themes replace the Customiser with the Full Site Editor at Appearance > Editor.
Can I revert a change in the Customiser?
While still in the Customiser unpublished changes, click Discard Changes. After publishing, you cannot undo directly — but if you have Jetpack or another revision plugin, Customiser changes may be versioned. Otherwise, restore from a backup.
What happens to my Customiser settings when I switch themes?
Settings specific to the old theme (colours, header layout, custom CSS) are retained in the database but no longer applied. If you switch back to the old theme, they reactivate. If you stay on the new theme indefinitely, you can delete the old theme to tidy up.
Is Additional CSS included in backups?
Yes. Additional CSS is stored in the database (in the wp_customize_changeset_ posts table and options). Standard database backups include it.
Can I preview changes on a specific page?
Yes. While in the Customiser, navigate through the live preview on the right to the page you want to see. The sidebar settings persist; the preview shows any page you click to.
Can I see what others have edited in the Customiser?
WordPress core does not track Customiser edits per user. For teams that need visibility, plugins like Activity Log or WP Security Audit Log record Customiser changes along with other admin actions.
What is the difference between the Customiser and the Editor?
Customiser is the classic-theme tool. Editor (Full Site Editor) is the block-theme tool. Different underlying models, different capabilities. Do not expect them to behave the same way.
Can I export and import Customiser settings?
With a plugin, yes. Customizer Export/Import is a free plugin that serialises Customiser settings as a JSON file. Useful for moving configurations between sites.
Why is my logo upload failing?
Usually a file size or permissions issue. Try a smaller file, or check PHP upload limits in Plesk. For SVGs, ensure you have a safe-SVG plugin installed — WordPress blocks SVGs by default.
Should I switch to a block theme and use FSE instead?
For new sites, yes. For established sites running well on a classic theme with customisations, switch only when you have a reason (looking at a redesign anyway, wanting features only FSE offers). Do not switch just because block themes are newer.
Launch your WordPress site on smartxhosting.uk
UK hosting with the Plesk WordPress Toolkit, LiteSpeed Cache, Redis object caching, free Let’s Encrypt SSL, free CDN and daily backups — from £2/month.
View WordPress hosting plans →