Working with firefox 57 but not in 52.50ESR

I need set "F1" key to run "inspector" in firefox ( default key is Ctrl+Shift+C ) Please help me to do it

It clears the cache (see page: about:cache), but i would like it to clear cache only for the site i am on. Do not want to loose all cached content, it is not effective.

55.0.3 (32-bit) the changes are not saved. At every FF start the addon revert on default settings, including "reload active tab" and "show notifications".