How to Clear Favicon in Firefox's Cacheby Allen Bethea
Sometimes it seems like it's easier to erase an embarrassing tattoo than it is to remove information from Firefox's browser cache. For example, you know that the favicon associated with a specific website has been changed, but Firefox will stubbornly continue to display the old icon in its browser tabs and Bookmarks list. Fortunately, Firefox provides the "Clear Now" button, which will enable you to empty its browser cache and display the site's new favicon the next time you launch the browser.
Click the "New Tab" button, then close all browser tabs with the favicon you want to clear.
Click the "Firefox" button, and then click "Options." If you are a Windows user and you don't have the Firefox button, click the "Tools" menu and then "Options." Ubuntu users should click the "Edit" menu and then "Preferences."
Click the "Advanced" panel button and then the "Network" tab.
Click the "Clear Now" button under the heading, "Cached Web Content."
Click the "Close" button, and then close down all instances of Firefox running on your PC. When you restart Firefox, the old favicon should not appear in your browser tabs when you revisit the site.