I'm only going to pick up on the "I want something with high pay" remark. Remember two things:
1 - the course you do doesn't come with a job role attached to it (well a few do, like vet med, but most don't). So a marine biology degree, a life sciences degree, a physiotherapy degree (to a lesser extent) doesn't mean you have to become a marine biologist or whatever. If it's something you enjoy and will give you the qualification to take you into a number of different career paths that are attractive to you, that's the main thing. You don't need EVERYTHING planned out now. Definitely wise to think about employment opportunities following graduation, but a uni degree doesn't need to be a blueprint for a specific job.
2 - You're talking about 4ish years of very hard work. People don't do that just because there's high pay at the end. (Well a small number who want to work in banking afterwards might, but 97% of humans don't operate like that.) There's no point in something paying well if you dislike it.