Thesis main author credit and prestige

Our thesis instructor, after rejecting our proposals, became one of our thesis advisers after we've accepted his suggestion. Every time he's telling us that our proposal doesn't seem like a thesis (in a mocking way), he inserts that we should do the "nobel" method he had discovered in detecting a feature/property in a sample. That's what his previous advisees did. Eventually, somehow against our will, he became our thesis adviser because he's the only one who knows the methodology and because he said that it was his idea.

One of the reasons why he also got us as his advisees is because he wants to submit an international paper (IEEE). He said it to our other thesis adviser.

I mentioned a while ago that his previous advisees applied his "nobel" method. We cited their paper as, let's say, A____ et al. with A being the last name of the student in their group who comes initially if their last names are sorted alphabetically. When we presented our paper to him, he said that it should be his name and not theirs because it was his idea and method.

I am asking this question because he might do it to us too -- claim that our thesis is his. Who shall get the thesis main author credit? If I may be permitted, I'd also like to know how to deal with our adviser who only got us as his advisees because he wants prestige after he claims that our thesis is his.