How To Enable and Disable Mozilla Firefox Add-ons

Firefox add-ons are enabled by default when you install them. Sometimes you might want to disable a particular add on temporarily for whatever reason.  Sometimes,  firefox will disable some add-ons and you want them enabled.

Launch Firefox. Click on the Firefox menu and select 'Add-ons'.   On the add-ons page select the add-on you want to enable or disable.
Use the same button to Enable and Disable.

Enable and Disable Add-ons on Firefox for Android:
You can also enable and disable Firefox add-ons on your Android device.  The process is very simple.
Launch Firefox.
Tap on the Firefox menu.
Tap on 'Tools'  from the menu.
From the tools menu, tap on 'Addons'.
You will see a list of addons.  Touch and hold the Add-on you want to disable or enable.

NB: The procedure on Firefox  for Apple is more or less the same.