How to Install Favicon in WordPress?
4) In order for your favicon to show up in some older browsers, you will need to edit your page header. To do this, go to your WordPress Administration panel. Click on Design then click on Theme Editor. Select the file called Header or header.phrp.
5) If there is one, find the line of code that begins with <link rel="shortcut icon" and ends with /favicon.ico" />. Overwrite it with the following code.
6) If you use WP-Cache, clear it, then Clear your browser’s cache. You may need to restart your browser, and maybe repeat the whole process twice
7) Open your homepage. Your new icon should be displayed in your browser’s URL box and/or tab.