It's often important to know what version of Firefox you are using, to help you troubleshoot a problem or just to know if Firefox is up to date. Here are two ways to find out.
Click the menu button
, click help
and select About Firefox.On the menu bar, click the Firefox menu and select About Firefox. The About Firefox window will appear. The version number is listed underneath the Firefox name.
Note: Opening the About Firefox window will, by default, start an update check. If an updated version of Firefox is available, it will be automatically downloaded. For more information, see Update Firefox to the latest version.