You're supposed to scream from your diapragm. Your vocal cords won't snap if you do it from your throat, but they will build up scar tissue which I believe can become cancerous. That will fuck you up lol.
When I first started, I could only do really low growls, but I learned how to get it higher by kind of an odd way. If you can growl deeply from your diapragm, try this.
Do jumping jacks or just jump up and down and growl words. Then make yourself bring the pitch higher. For me, when I'm jumping, it makes me growl from my diapragm even though the pitch is going higher. I dunno if that will help you or not, just tellin a story.