If you want to change your course, you need to bear in mind the deadlines set by your school. Once you miss the deadline, you have to wait for another semester before you can possibly change your program. You need to get approval from your current school and the school you want to transfer to. They normally look at your current GPA and admission scores and your statement for reasons of change. Some special schools, especially some arts school, may even require you to submit your portfolio as part of your application.