First, see what you like. What you like is very important. For example, I used to be a science student, and I was good at math and physics. As a result, I used a little math in college (and it has little to do with high school), which can be said to be completely useless (I studied management). You said you were good at math. If you like math, choose math as your major. Of course, there are many branches, such as applied mathematics, statistics and so on. It depends on your choice. If you like history, you can study history. If you are willing to watch more and learn more, you can easily bridge the gap between college and high school with snacks.
Second, apart from some majors such as science and engineering, there are some requirements for some basic mathematics and physics in high school, and others have little to do with it. Moreover, the university can be said to be far from high school, and many things have to be re-studied.
Third, learn as much as possible, study extensively, and constantly absorb things like a sponge in the undergraduate stage, and learn a little in all aspects. I hope it works for you.