I'm a pretty good singer when my voice doesn't crack, and I've already passed puberty so it's not that, I'm also an alto... how do I fix it?
yes, warm up your voice before you sing. Try pressing your lips together while humming a really high note. And at the same time, do that thing where you kinda.. make your lips vibrate. Like sharpay in high school musical (sorry for sounding lame but that's the way to do it). Rember to be relaxed at the same time and not force the high notes to come. And go slowly from regular to a little lighter, to even lighter than that, to a little darker, to lighter, lighter, lighter.
do some warm ups before you sing if that doesnt work you will just need to prwactice more and more or you can get singin lessons.
