My grandpa was an old cowboy and had the BEST fix for this! I will have to try to look up the knot so I can tell you...
First tie them to something they cannot pull loose, or a halter that will break. Take a lunge line, rope, etc, and attach it to the halter and then over whatever you are tying them to. DONT tie it or wrap it around your hitching post. Take it and wrap it around your horse, around the barrel, where a girth would go. Then you tie this knot (I will seriously find it and edit this!) When they pull back, they squeeze the crap out of themselves, and when they step forward it releases. They teach themselves! Its amazing!
Also, they only learn to stand by standing. My horses have stand camp when young, where they are expected to stand quietly until I say so. If their feet are moving they do not get put away!! And they dont just stand where they get tacked up, I tie to posts in arena, the trailer (if its hooked up), a nice tree in the pasture, whereever I feel like. They learn to stand whereever I stick em!!
There is just as much horse sense as ever, but the horses have most of it. ~Author Unknown