Annoyance and maturity.

[distant gulch]

Well for one, your profile says your age is 13, so if that's accurate then when you say "mature" that's a pretty relative term. For another thing, your voice sounds different to yourself as you're speaking than it does to people (and microphones) listening to you.
The "sounds like a 12 year old" thing may be caused by the fact that inside your own ears, certain frequencies that sound "bright and nasally" are quieter and others that sound "low and full" are louder than what it sounds like to other people. That's just a fundamental aspect of recording your own voice that you'll eventually have to get used to if you want to keep doing it, and just know that what you're hearing is how you sound to other people.

[tepid dragon]

Ohh icic

[spiral topaz]

question How can i improve my voice or change it that it doesnt sound that weird

[distant gulch]

Seems like the original poster deleted their question, but it was very similar to yours. The answer I gave them above mostly covers your question—because of how sound works, your voice sounds different to your own ears than to everybody around you. So unless you have an actual speech impediment (in which case, that would be something to talk to a speech therapist about), your voice "sounding weird" is actually normal and just something you have to get used to if you want to record yourself more.

[spiral topaz]

And yeah I found out that that my Mic is also a problem

I sound scratchy and young /like a fortnite kid when the mic is just A arm long or half a arm long away and that sucks so I really have to have it real close what sucks sadly

But means I need an good mic arm that k have to put on my Hyper x microphone and is not in the way of my Monitors or something so it's just like next to me or under me