Any Arabian fans out their, I have an Arab question!?

Ok so, in an all Arabian horse show, when you do hand gallops, does your Arabian horse have to be setting their head at a hand gallop? Or how does their head have to be? Also how can I learn to keep my horse's head set when I'm doing any type of transition? He likes to throw his head up, even when I'm in his show bridle/ kimberwick bridle! Please Help Me. Thanks!!!!!!!!!