Assuming you’ve Mozilla Firefox already installed on your PC let’s first check the version of Firefox installed on your system via terminal. Open the terminal (hit Ctrl+Alt+T to open) and type this :

firefox --version
# displays the current version

Next enter the following command and hit enter:

sudo snap refresh firefox

Don’t open the Firefox browser while typing in the commands otherwise it does not work. Then, follow the prompts on the screen to update Firefox to the latest version.

You can use this technique in case you’re having trouble updating Firefox via the Linux App Store on Ubuntu.