How long before I should quit my job?

I am 17 years old and I have 2 jobs right now. One of my jobs, I work at a house for mentally challenged people and I love this job. I work every other weekend friday through monday, 10pm-2pm the next day and it is really easy, it is about 42 hours a week and I make about $700 a month just on that job. My second job I work at a grocery store in the produce department, and I really hate this job a lot I have been there about 3 months. I work about 15-30 hours a week and that's not so bad, but I hate my bosses they barely trained me and I get yelled at for every little thing I do that I didn't even know about and i am getting sick of it, also the other people I work with are not so friendly to me like if i am working by myself they will give me a hard time about how I work and they will literally take me in the back and yell at me at the top of their lungs. I just wanna know if I quit now, would that look bad if I try and get another job. Or is quitting because i have 2 jobs reason enough?

It will not look bad, you shouldn't be treated badly because of the managements issues. They should have trained you correctly. The other workers there are supposed to be friendly, and they really have no right to yell at you. They should sit down with you, and tell you what you're doing wrong and what you should do, resolving the issue nicely. Anyway, quiting won't look bad, tell them You appreciate the chance to work there but you're quiting because you are working another job. Also, if the new place you are trying to get a job at contacts the grocery store, legally they aren't allowed to give you a bad reference. And plus, if you're constantly being yelled at theres a good chance you could get fired, and quiting looks way better than being fired.