***This is better to do from a computer***
I had the same question. You can change it actually. Go to one on the emails you get from Apple Music. At the very bottom of the email there are a part that said ''Manage'' and below it says ''Account'' so you are going to go there. Then this page is gonna pop out, so you're going to again to the very bottom below "account'' again where it says "Manage your Apple ID'' and then enter your current Apple ID. Then your phone is going to ring asking ''Don't Allow or Allow'' and you are going choose ''Allow'' and a code is going to pop out and you are going write that code. And then you are going to see the option to change your email. If you follow the instructions after that, you will be able to do it. Good Luck!!!!