I am not sure what you mean by yelling to break an encounter? Totally in the dark there lol
The first picture posted - 3rd row, 2nd and 3rd icons = yell (as in yell for help) - basically, when you fight mobs, the encounter is locked to your team - so any passersby can't kill-steal or help if you get into trouble (i.e., mobs unattackable to them). When you /yell, the encounter is unlocked and passerbys can help get some mobs off you. Even when there is no-one around to help you, it is sometimes good to yell for help to avoid training a huge chunk of mobs all over the place (i.e., sometimes they reset back to their original positions faster - not all the time though). Once you yell though, the mob/s gives no exp or loot.

As for shifting between hotbars:
- first hbar - default = shift+1, shift+any other number = non-default
- second hbar - shift+alt+2 would be the default, any other number for non-default
- third - shift+ctrl+3 = default, any other number = non-default

So you got your xkeys to shift into the hbar - I assume it's just a matter of putting in the relevant 'default' command to revert back (i.e., shift+1 or shift+alt+2 or shift+ctrl+3)