Do you have access to a round pen? It would make dealing with him a lot easier. Also, you might try to get some advice from a local trainer if possible. Sounds as if he is treating you like one of his buddies and needs to know that is not the case. With our horses that forget who the boss is we occasionally use a chain lead under the chin for a while. Using it firmly but gently gets good results. If you have never used a lead with a chain get help from someone who has before attempting it.