I'd agree that "computers" is almost certainly not the best example. Self-teaching how to program is probably one of the easiest topics to jump into out there. And it has the benefit that, if you're really pretty sure you want to major in computer science (which may or may not actually be the best choice for someone who is just "interested in computers") learning how to at least program and doing some projects, etc. is one area of self-study that will be very valuable when you start university.

As has been discussed here at length before, for better or worse, good university computer science curricula tend to assume you know your way around a computer and can program--or you have to get up to speed very quickly on the side.