How can I find devices linked to my number?

My settings change by there self. I check running apps all the time and it's not normal. Apps download on they're own . I don't have an iPad or computer but yet my phone says I'm linked to both I see that I'm connected to a business which I shouldn't be I'm also connected to a classroom as a child yet I'm 42 years old and I own this device I can't access things an owner should be able to who ever is doing it is almost undetected but I know something is wrong. I just want my privacy back my camera is getting used microphone. My phone never sleeps I turn battery saver on n it turns off by its self it's really frustrating

I have bought the phone brand new. It's an Motogplay I bought it at Boost mobile. I'm on a family plan with my boyfriend. I so afraid that it maybe him. Maybe trust issues?? Whatever it may be I need to find out. I'm entitled my own privacy. Open source project is also monitoring me and I just need to know how to make it all stop. I really appreciate you tryning to help me