It's not so much that he changes his mind. I mean, that happens in the creation of fiction all the time, and it's really quite interesting to see how a story can evolve away from what you originally intended it to be. But he either refuses to believe it ever changed or tries to convince us by changing his movies that it never changed. It was always meant to be this way, and anything that differs from that is just either the technology of the time or the crappy studio system that prevented him from doing it the way he wanted it.