If you don't want to study mathematics all your life, you'd better change your major.
Speaking of employment now, engineering should be the best job, such as machinery, civil engineering, electricity, engineering mechanics and so on.
It's ok for a university to change majors. Generally (at least in our school), you can change your major next semester and then apply.
Freshman must not fail the course last semester, and it will be easy to change majors if you get better grades.