Customizable Shortcuts is a Firefox add-on which allows you to change all the default Firefox keyboard shortcuts. Once you install this add-on in Firefox, you can customize the keyboard shortcuts in Preferences dialog and go to the Shortcuts section.

It is very easy to use, just open the Shortcuts option in the Options window and select any key that you want to edit. Now click on the Edit button to edit the key and change the existing key with a new one. Once you customize any key it will be highlighted in bold so that you can easily know which key you changed the last time. If you have done something wrong with keyboard by mistake, you can press the Reset button. Reset button easily reverts back all the changes and sets all the keyboard shortcuts back to default.