Try to yell using your diaphragm. I'm an MTI (drill sergeant) in the USAF & that's how we're told to yell to preserve our vocal cords. For whatever reason, I'm completely fluent whenever I have to yell at someone (or a group of 300 someones haha) now. Once you figure it out you can be super fucking loud without straining your throat at all. I found that it actually helped out in everyday speaking too, since it got me in the habit of taking a breath & establishing a more regular breathing pattern even when talking normally. The easiest way I can describe it to you is to start with a single syllable phrase, like "hut", & belt it out like you just got punched in the stomach & got the wind knocked out of you. At some point you'll start to feel it & know that you're doing it correctly. I'm sure you can probably find some resources online that could explain it better than I ever could.