Generally, there are two opportunities to change majors.
1, when entering school. But it is very difficult at this time, unless the grades are good and both departments agree, so it is generally better to know the teachers in advance.
After studying for one year. At this time, write an application first, and then several schools need to take exams. Only after passing the exams can they transfer. Most schools apply first, and then examine and approve. However, you did better in the first school year and performed better. Generally, only the top students in the class or students with the same major are eligible to transfer. The requirements for transferring to other majors in the same college are lower, while those for transferring to other majors across colleges are higher.