I spent a year with a Phd. supervisor. I am not happy from both aspects: relationship and academically. Is it ethical to change the supervisor? Should I explain the reasons for change in details to the prospective supervisor or just be brief? How to avoid getting the impression that the student is trouble-maker (if I explained details of problems) vs. avoid give the impression there is no real reasons for change or that the student is not serious enough (if I am brief)?