You can also modify your site's favicon (this favicon will be displayed on your browser's tab). You need Confluence admin rights to make changes.
- Go to
> General Configuration > Site Logo and Favicon . - Find your image file and select Upload .
You can upload PNG, GIF, JPEG, or ICO files. The best picture state is square, with a minimum of 48x48 pixels.
https://www.cwiki.us/display/CONFLUENCEWIKI/Changing+the+Site+Logo