ARMY ROTC Scholarship questions?

I am applying for my ROTC scholarship. My main academic major intent is Psychology. Most of the intended schools I have listed offer psychology. However, one of the schools is mostly engineering based. If I should decide to utilize my scholarship (If I get one) at this school (Embry Riddle), can I change my major, or do I have to stick with my "intended" major? Also, is it easier , in a way, to obtain an Army ROTC scholarship, than an NROTC scholarship?