too many interests = undecided major

Some applicants have a clear defined major in mind like CS or Finance or Pre-Med while most are not sure or undeclared.

Since most college graduates change their major 3 times as an undergrad on average, I don't think it really matters much what you put down. Nevertheless, it should be in the ballpark. So if you are interested in humanities, put a humanities major down. And if you are interested in STEM put a STEM major down.

But you should put something down that aligns with your HS academics and ECs narrative. So don't put CS down if you haven't learned how to program anything yet, or are not in CS related ECs like robotics or tech support. Since CS is a really popular major at top colleges, unless you feel you can compete with the best of the best, I would avoid putting it down as major. For example if you goal is getting into Stanford and that goal outweighs what major you declare, then focus on the least subscribed majors at Stanford like History or Linguistics, or Environmental Science.

I think on Naviance.com there are various tests you can take to help narrow down your majors. Also there are dozens of books you can read to help you.

Just search on Amazon or your public library. You will find many books that are focused on this.

Hope this makes sense. And good luck.

keep in mind that you can double major! also, liberal arts schools tend to suit the issues that you just laid out, as if you become uninterested in one field of study, you can always switch to another one. many colleges/universities are too specialized for you to do this in, so be sure to pick one that has a wide variety of majors and minors, and one that is well balanced in the sufficiency of education in all fields.