Your new instructor sounds like she has a very shallow knowledge of her job. Maybe she has done what her trainers said without ever LEARNING the whys.
I LOVE how you put it. I run into number of trainers, who were probably taught what they try to teach when they were riders. But have no knowledge behind that, and in fact can't deal when situation is not typical.
A REALLY GOOD instructor is a diamond hard to find.
I don't argue with my current instructor, because I truly think she's great. Not just teaching (that even the dumb person like me understands
), but also explaining why you have to move this way and not that based on the skeleton, movement, and balance. However I ask lots of questions, some not easy to answer (just a habit, I usually can't proceed with something without the complete understanding of reasoning behind it).
Also another (old) instructor I started to take lessons again with tells me all the time I'm wrong, my horse doesn't go right, etc. While it's not pleasant to hear of course, it's a truth I have to deal with. She tells me HOW to deal with it though with explanation of why it'll help. So I'd never even think to argue with her.
However there are instructors out there who are plain bad - don't teach you anything, can't answer questions, etc. Then I just try and leave, arguing won't take you anywhere.