You don't have to teach your horse to do anything. You just have to allow them to do it, and you are really teaching them. You are teaching him that he is allowed to walk off when you are mounting him. You are teaching your horse that it is acceptable for him to pin his ears back at you. It is very important that you understand that horses don't understand English.
Horses understand action.
So when my horse pins his ears back or acts disrespectfully towards me in any way, if I put pressure on him and reprimand him for this behavior, he soon figures out that it was uncomfortable for him to do that. Horses get away with whatever you allow . If you let your horse be disrespectful and act like an idiot, believe me -he will do an excellent job of just that. If you let your horse act respectful, patient and obedient, he will very quickly be respectful, patient and obedient. Horses learn through repetition .