So, I know everyone is going to say it shouldn’t matter what people think of me, it’s just sometimes it seems that people think I’m mad all the time or maybe that I’m rude. I’m not rude (I always try to be nice) but my face looks angry always (apparently). People don’t like that and maybe I look ugly to them because of that and they won’t talk to me because I don’t look friendly. I don’t know, should I change how I am? Should I be more fun so people like me?
Why don't you ask for some feedback from your friends? Ask them what you could do to look more friendly and open to positive interactions. Improving how you come across to people and what your face communicates are skills that will get you through a lot in life.
You should never change yourself to make other people like you. Maybe you should ask your friends how you could look more friendly but there is no person in the world that smiles 24/7.