web browsers
Uninstall Firefox and replace with the Firefox Extended Support Release so that you don't get forcefully upgraded to the dreaded Quantum 57.
- Open Software Manager
- In the search box type "Firefox" and click "remove"
- Launch Software Sources (Menu button - Administration - Software Sources)
- Choose PPAs and +Add a new PPA
- enter: ppa:mozillateam/ppa
- Click "update the cache" and close Software Sources