You need to teach your horse to move away from pressure, something that's unnatural to them. If the horse moves away from pressure well and still sets back when tying, try tying way above his head so he cannot get much leverage. You could also buy a blocker tie ring, they're expensive (in my area) but they work. If the horse has nothing to pull against, he won't pull. There are also halters you can but that have spike-like things on the part that's on the poll that makes the horse uncomfortable when he leans on the halter.
Every great dream begins with a dreamer. Always remember, you have within you the strength, the patience, and the passion to reach for the stars to change the world. ~Harriet Tubman