Absolutely you can change jobs, but there is a process. Any open position will be advertised on campus, any student can apply, recognizing that some jobs have specific criteria attached to them.
A student would submit an application (which can be found in the Work Office) to the hiring supervisor. If a position isn’t available but you still want to switch departments, in some cases students have been able to switch one student worker for another. This takes a bit of work and great communication on your part, you would start by speaking to your current manager about your interests and they would work with you to connect to the department you wish to move into. Again, this doesn’t happen all that often, but it is one means to make a job move.
The final way to change jobs is at the end of the spring semester, any position not filled by a returning worker (someone who held the job that year) will be open to campus for student applications.