How to update firefox?

[noone]

[Dominic]

Click the Firefox button, click the right arrow next to Help, then click on About Firefox. It'll automatically check for the latest version and compare it to your installed version. If the latest version number is greater than your current one then it'll download and install for you.

– Dominic

[Sophie]

At the top of the Firefox window click the Firefox button then click on the Help menu and select About Firefox.
The About Firefox window will open and Firefox will begin checking for updates and downloading them automatically.
When the updates are ready to be installed, click Restart to Update.

If that doesn't work, just download a new copy from mozilla dot org