Hi it`s me again,
I just found out that if you press Shift and apple menu, the force quit option is changing to
force quit +application name which is selected.
So if Firefox is not responding and you press shift+ open apple menu, you will see an option Force Firefox Quit or something like this. You can also try, but i`m sure this was mentioned before, to hit ALT+ Apple Menu and you will see other helpful Commands.
I hope this helped anyone.