Can you reverse the rotation on your stihl weedeater?

Naw man. The threads are reverse threaded. It will loosen when under load. That and most trimmer heads are made for counterclockwise rotation. You have an issue along do. The simple cure (most don't realize) if you hold the trimmer left handed on your left side of your body, right hand on throttle and left controlling the trimmer, Most pro level trimmers are made this way and it's a small learning curve to hold it left BUT it actually is the right way though it doesn't feel natural at first. Trust me.. ;)