By default Quake doesn't allow you to change your weapon hotkeys which can be a bit annoying in a heated battle.
I'm gonna show you how to change your weapon keys without having to play keyboard twister or scroll like madman to get to the desired weapon.

1.Go to Quake\id1 folder (hipnotic and rogue for the expansions)
2.Create a new text document and rename it autoexec.cfg
3.Inside the cfg file copy/paste the following for the base game, Scourge of Armagon and Dissolution of Eternity:

bind "1" "impulse 3"
bind "2" "impulse 5"
bind "3" "impulse 7"
bind "4" "impulse 4"
bind "g" "impulse 6"
bind "x" "impulse 8"
bind "MOUSE3" "impulse 1"
bind "MOUSE4" "impulse 2"
bind "F5" "echo Quicksaving...; wait; save quick"
bind "F8" "echo Quickloading...; wait; load quick"
bind "END" "quit"

bind "1" "impulse 3"
bind "2" "impulse 5"
bind "3" "impulse 7"
bind "4" "impulse 4"
bind "5" "impulse 225"
bind "g" "impulse 6"
bind "x" "impulse 8"
bind "z" "impulse 226"
bind "MOUSE3" "impulse 1"
bind "MOUSE4" "impulse 2"
bind "F5" "echo Quicksaving...; wait; save quick"
bind "F8" "echo Quickloading...; wait; load quick"
bind "END" "quit"

bind "1" "impulse 3"
bind "2" "impulse 5"
bind "3" "impulse 7"
bind "4" "impulse 4"
bind "g" "impulse 6"
bind "x" "impulse 8"
bind "MOUSE3" "impulse 1"
bind "MOUSE4" "impulse 2"
bind "F5" "echo Quicksaving...; wait; save quick"
bind "F8" "echo Quickloading...; wait; load quick"
bind "END" "quit"

If you don't like these bindings you can change them to whatever you want
These impulses represent the following weapons:
Impulse 3 - Double-barreled Shotgun
Impulse 5 - Supernailgun
Impulse 7 - Rocket Launcher
Impulse 4 - Nailgun
Impulse 6 - Grenade Launcher
Impulse 8 - Thunderbolt
Impulse 1 - Axe
Impulse 2 - Shotgun

Impulse 225 - Laser Cannon
Impulse 226 - Mjolnir