So I’m going to be brutal without intending to be unkind, even if it may come across that way.
Totally agree with the poster who remarked that you are way over-horsed, here. You aren’t riding this horse well at all, and the horse is upset about it. This looks like one of those horses that will reward a rider who gets it right, but who has no leeway for one that does not. The rider learns, but learns the hard way. It is actually rather generous of the trainer to allow you to keep trying with this horse. I’m guessing that she’s hoping that you’ll start to understand what works and what does not. But the penny hasn’t dropped yet.
It’s possible that the instructor is too far over your head as well, and that you need someone who can communicate in a way the you’ll understand better. This instructor is trying, and you are trying, but it looked to me like neither of you is understanding the other.
I salute you for hanging in there and trying, because you are clearly being challenged. I think this instructor believes that you can learn this, and that’s why she’s hanging in as well, even though you have a long way to go.
However, from her remarks I think everything she is saying is going right over your head. I don’t know if you have an earpiece to hear her during your ride, but regardless if you hear it then, or later, you aren’t making much adjustment to align with her coaching. I don’t think she’s using a riding language that you know very well, frankly.
What I see is that everything about your seat and riding position is sending this horse into orbit. He actually seems to be making some effort to restrain himself and not just bolt, and that’s probably why the trainer is allowing you to keep trying.
I realize that this is the h/j forum and perhaps your position is an h/j position. But it is all wrong for this horse. And it would be wrong for most horses that have been trained and wired the way this one seems to be, more of a high-powered dressage type. Your body is in a C, your shoulders are way far too far forward, and your elbows are often locked. Your hands are bouncing (no wonder she is trying to get you to use the horse’s shoulders as a reference point to help keep them still). Your legs are stiff and not flowing with the horse. This is all basically the opposite of what the instructor is trying to get you to do, of what it looks like this horse would respond to.
I admire your grit for hanging in there, even if I think a lot has to change on your part. I can totally see that there must be some moments where the horse makes you feel that he’s about to do something radical. But somehow the two of you make it over that instant.
I believe that you are correct that it is you who needs to change, not the horse that needs to be re-trained.
Just IMO, but to ride this horse, you basically need a complete overhaul of your riding position. I’m going to leave that up to your instructor. With the caveat that you and the instructor have got to get on the same page. She has to communicate in a way that you can understand (she’s more general and not very specific), and you have to learn more about what she is trying to say to you. Those two things seem to both be missing in the videos. I think you need to tell her the conclusion that you have reached here, that you are accepting that this change is on you, not the horse, and that you want to better understand what you need to do, and you need her help to do that with specific pointers.
This is a moment in anyone’s riding career when they decide what they want to do with their riding. If completely changing all you know so that you can ride a different way is something you don’t want to do, and don’t need to do if you been satisfied previously, then it’s best to move on to another horse better suited to what you enjoy. But if you are interested in diversifying your skills and give something new a try, learn what this instructor is trying to communicate (even if it would be best to learn it from someone else) and hang in there. I don’t think it will be quick, but who knows, maybe it will click and you’ll see results fairly soon. 