'Push' your horse around, accept no crap and make sure YOU are putting on the pressure and that he is 'yielding' to that pressure.
Never step back away from a horse,
always turn your horse to the right,
never let him take a step past you or go around you,
make him move his shoulder away from you every single time you get a chance,
make him stand still on a loose rope -- never try to 'hold' him still,
back him up often,
if he takes an unwanted step forward, make him back 5 or 10 steps.
NEVER, NEVER let him set the agenda. You need to call all of the shots. It makes absolutely no difference what he does or where he is in the herd pecking order. Each 2 horses or horse/human pairs has a dominant and a submissive member of that pair. Some 'lead horses' only are the leader of part of the herd. Any set of horses I have (some fields have 10 or more) ALL think I am god. They are attentive, want to be near me, but never show ANY form of dominance toward me or around me. They do not 'boss' another horse in my presence. They do not lay an ear back at another horse when any of them are near me. They are 100% respectful. That is what you need to learn to achieve. Your horses will tell you when you are getting it right.