autofollow will work if your priest has a target and i think resolutions listed in game setting will work because i tested them at the time i made it, to see if the resolution you're using working or not, try pressing alt-w while active at priest window and check if the clicking is accurate.
if somehow it stops working after changing resolutions, you should restart the game after set it to one of the default listed resolution [not custom res].
i don't rely much on this for my priest, instead i set my botting area at max 10-15m radius in zpw so my priest will just stay up there when giving buffs/healing without moving an inch.