anywayz here's the solution

so herez the solution.

type about:config in the address bar and press Enter.

1. Right-click anywhere -> New -> Boolean
2. it will ask for name put Name: extensions.checkCompatibility
3. it will automatically ask true or false make it false.
4. restart firefox.

this is ultimate solution for making any addons work for new version of firefox.

also if you want to install any addon to you existing new version of firefox and
firefox website says

This add-on is for older versions of Firefox

download the addon from other browser and drag it onto firefox