Don't target another player, target a monster.

You use beneficial skill on yourself, right?
Cure/sacrifice, when you target a monster go in a subtarget-mode, and you can target yourself or another player.

If you are a thau/conj, when you are at Aoe/single target step, you can change target.

There is not a problem with cure, the problem happens when we have to change an enemy fastly with melee attacks.