What is wrong with high schoolers and cliques in my school band?

You can’t change someone, or even make them see what they are doing or how they are acting is unfair. Your best bet, until you become Sr. Drum Mjr. is to stop trying call her out in front of everyone. It’s like trying to tell your manager what to do, even if they know they are wrong. Everyone will heir on the side of the manager, just to agree with the majority and stay out of the fire. In life this holds true no matter if you are speaking about religion, politics, ethics, etc…People will always think they are right and you cannot change them good or bad, they must learn from their own actions. So stay true to yourself and then after she reams someone next time, take them aside later and let them know it’s not their fault and to keep trying their best. You will make a great Sr. Major next year, hang in there your time is coming!