Hi Deborah, where is thriller? For example: * It's a new tab page wallpaper. See: [[Customize your wallpapers]] * It's a theme affecting the toolbars at the top. See: [[Use themes to change the look of Firefox]] * It's an add-on of some kind -- please describe its behavior in more detail * It has replaced your regular home page. See: [[How to set the home page]] and/or [[An extension changed my New Tab page or home page]] * It is a tab that keeps coming back after you close it -- please describe in more detail (for example, at startup, or in other situations) * It is a bookmark on your Bookmarks Toolbar -- try right-click > Delete Bookmark * Something else -- please describe in more detail