how can I get along with people are to immature?

First of all, don't worry. It's perfectly normal for good フレンズ to have different personalities. :)

If this childishness is causing tension between あなた and your friends, I'd suggest あなた focus on what あなた do have in common with them. What hobbies do あなた have? What TV shows and 音楽 do あなた like? Find a common interest and take it from there.

Being mature does not make あなた "lame"! It's important to just be yourself. If あなた spend your teen years pretending to be someone you're not, あなた will regret it when you're older, so be true to yourself. If your フレンズ try to pressure あなた into changing your personality again, try asking them, "why can't I just be me?" It might not seem like a very complex question, but it might help them realise that trying to change who あなた are is wrong.

Think back to how あなた became フレンズ with them. あなた mentioned that あなた pretty much get along, and that's good! So, why do あなた get along with them? How did あなた become フレンズ in the first place? There's obviously some reason あなた two can get along well, so focus on that too.

So, long story short: find common interests, remember why あなた are フレンズ in the first place, and be yourself!

Good luck! :)