How do you switch targets in combat? If I'm fighting one player and then wish to hit another, what is the command to change who you are fighting? Same for when you are fighting a mob and some player attacks you how do you change without fleeing.

I've tried murder and all it says is 'one battle at a time', tried aim,hit.
I must be having a blonde moment as I can't figure it out and don't see it on the help files. I see other people do it all the time with the echo 'starts aiming at you'

Thankyou