SBE course: invalidate correct/incorrect answers of quiz if you change the answer

If you answer a question and check the answers, and the answer is OK, you get a green highlight and an indication with text that the question is answered correctly. If you change it afterwards, it remains indicated as correct. Somebody following the course found this confusing. I think we should invalidate a question and the entire quiz (but not the other questions) if you change your answer for a question.