I was used to press Control+1, Control+2 and so on to switch between tabs in Firefox. Now, in Unity, I have to use the Alt key instead. How can I change that?
There is a nice add-on you can try called KeyConfig available from here. Unfortunately the author hasn't added this to the official Mozilla Addons.
If you still want to try this "untrusted" add-on, click on the keyconfig.xpi and install it. Then go to your firefox addons to display various keybindings offered by the addon
Click on the box shown by the arrow and choose your key combination - CTRL + 1.
This will change the value in the box to CTRL+1. Click the Apply button
Repeat for the rest of the "key_selectTab" values.
It's easy to change manually:
You can also search for addons that may do it more easy, but changing the accelKey number in about:config is not that hard.
I've added support for this to my Windows Shortcuts extension (version 0.2).
It's a trival extension with no options.
It sets these shortcuts: