F2 is the quick way of changing your weapon/armour/shield/mag without going to F12.
Pressing ctrl+end together is the most efficient way to change your weapon in game . You can also access mates/atomisers/telepipes etc and techniques from this same window by pressing the right arrow key.
If you're referring to customising controls then you need F12 for that .
Feel free to annoy Chuk if you have any further questions, he never has enough work.