Firefox Extended Support Release

The Firefox Extended Support Release so that you don't get forcefully upgraded to the dreaded Quantum 57.

GUI WAY...

1. Open Software Manager
2. In the search box type "Firefox" and click "remove"
3. Close Software Manager
4. Launch Software Sources (Menu button - Administration - Software Sources)
5. Choose PPAs and +Add a new PPA
6. enter: ppa:mozillateam/ppa
7. Click "update the cache" and close Software Sources
8. Open Software Manager
9. In the search box type "Firefox-esr" and when located "install"

CLI WAY...

sudo add-apt-repository ppa:mozillateam/ppa -y
sudo apt update
sudo apt install firefox-esr

See also: Firefox , Favorite Firefox Extensions