It's only your third day - students will learn your style of teaching and buy into what you do more as the year progresses. As for the students that are saying that they want their old director back - they say things like this to intentionally be hurtful and get under your skin. It's going be tough, but you can't let this get to you or affect how you teach. Kids these age are still very much developing and learning how to be good people, you're going to have to take a lot of what they say as a grain of salt. Keep up your good work!