How do you know which career or major to choose?

That is a very good question and one that needs to be asked early and often when considering which field of study to pursue. Here are some thoughts to consider:
1. Look at your past experiences. What do you enjoy doing. Not just the physical aspect like putting models together, but the characteristics behind it like paying attention to details, problem solving, working with your hands, building things, etc.
2. Spend time looking at different job openings using the key words you just identified. Look at the job descriptions. Most of them are scary when you read them and are intended to discourage the casual job applicant who is not committed so don't get discouraged. Look for the characteristics required to complete the job like problem solving ability, analytic ability, software skills, etc.
3. Record the types of jobs that appeal to you by their job classification like engineer, analyst, manufacturing, management, accounting, etc.
4. Consider the type of work being done. Is it something that is likely to be a repetitious activity where you do the same thing every day, something that provides a unique challenge every day, requires a lot of decision making or just following a formula?
5. Go back to your list of things you like to do and see what matches up.
6. Now you have a structure of things to look at when reviewing the various degrees offered by the college you are considering.

Don't worry if you get to College and find that you actually don't like the path you have decided on. This is a common problem and something that can be corrected pretty easily. Most colleges have a basic curriculum for all degree programs. Take the basic classes during your first semester and meet the other students and professors in your desired field. Question them about their experiences and knowledge about the field. If you decide you are not interested after-all, it is easy enough to look at the other offerings and get more information. School councilors in High School and College both will have a lot of information so don't hesitate to use those assets.
There is a book ("Strengths Finder 2.0") that can be purchased on Amazon pretty cheaply. It can also assist in identifying what your strengths are and help point you in the right direction for options.
Personally, I thought I had identified a career that I liked when I entered College, but I changed my major 4 times within the first 2 years after meeting other students and advisers in the different areas. I settled on a completely different field, changed colleges, got my degree and went to work in that field. Those experiences highlighted things that I really enjoyed so when it came time to change jobs, I looked for opportunities in those areas. I am currently doing something totally different from what I got my degree in, but all my experiences added to the qualifications needed for my current role. Your first choice is not going to be your final choice unless you are one of the few folks who can actually do that. Keep an open mind and if you find you are on the wrong path, be willing to change. You will have learned something in the process that will help you in the future. Never stop learning. Good luck!