WordPress calls the site-wide favicon a Site Icon. Preparing a clear square source is the most useful part of the process. You can use a logo, a monogram, or another mark that remains recognizable when reduced to a tiny browser tab.
Prepare your image
Create or upload your artwork in the generator, choose a square composition, and export a 512 × 512 PNG. A transparent background can work well, but check the light and dark previews. If your logo contains a full company name, consider using its symbol or first letter instead.
Find the Site Icon control
The precise administration screen depends on your WordPress version and theme. Look for the site identity or Site Icon control in your site’s general or appearance settings. Use WordPress’s current documentation if your screen differs. Select the prepared image and save the change.
Let WordPress manage the output
When you use the built-in Site Icon feature, WordPress can generate appropriate derivatives and output the icon declarations. Adding a second set manually in a theme or plugin can create duplicate tags. Inspect your page source to see what your site actually serves before adding more code.
When the icon does not change
First open the current icon URL from your page source. If the file is old, clear the relevant WordPress cache and CDN cache. If the file is new but the browser tab is old, try a private window or clear the browser’s site cache. Also check whether your theme or an SEO plugin is adding another icon.
Check the result outside the dashboard
View a public page while logged out and inspect it with the favicon checker. A site behind a maintenance screen or authentication wall may expose different HTML to visitors and crawlers. Google’s display of an icon can lag behind the website and is subject to its own requirements.
Reference: WordPress: create a favicon. Administration interfaces change; follow the instructions for your installed version.