Let your trainer work with you on dominance and ground work - that is just as important, maybe even more so, as learning to ride. It is what makes a rider into a horseman.
Too many people "fuss" over their horses. Oh Trigger, put your head down please. Oh Trigger, don't step on my foot. Oh Trigger, just stand here. Oh Trigger, why won't you let me put your bridle on.
That's the wrong attitude to have. You need to be more like.... PUT your head down. STAND here. And then you won't have the issues of getting stepped on or a hard to bridle horse. Your trainer did the same thing I probably would do, by using her entire body to control the horse. But she probably needed to do that to get the point across to the horse who was already in the mood to walk all over people. If she consistently handles the horse, she most likely will find that she no longer has to use her body to push the horse into standing still. The horse will know that he HAS to stand still for her because she consistently makes him. When a new handler comes into the picture, the horse knows that the consistency just went away so he no longer feels the need to stand in one spot. If you are the "fussy" type of handler, you are not giving your horse the consistency he needs. If you make it a demand to stand still, each and every time you handle the horse, the horse will start behaving for you.
Demand is not about force or strength or abuse. It is about guidance, consistency and discipline. When you tell your horse to stand, what do you do if he starts moving around? If you've let him get two steps in, you've just lost the guidance & consistency part of the equation. You should know the way of the horse well enough to know when the horse is going to move before he actually moves. When you see this happening, you can give the horse guidance to let him know that he should not be thinking about moving. If you aren't quick enough, maybe he'll take a step or two, but you will be there to guide him back to the original spot. You need to be aware of your horse at every moment so you can give him the appropriate guidance & consistency.
Discipline comes at the end of the formula when you know that the horse has gotten the appropriate amount of guidance, and you've been consistent about it, but the horse still has trouble doing the right thing. By this time, he should know what you want from him, and he should have been able to do it successfully. Sometimes an appropriate amount of discipline is required to get the horse back into complying with your demands.