Mouse/screen moving problems

Using a Logitech G502 gaming mouse - mouse moving insanely fast when I play League. Even when I turn the mouse sensitivity down to 0 it still moves like its on 50 on a different computer. I have to play on 10 or 15 sensitivity and it feels weird, like its still moving too fast when I'm clicking to kite in team fights and too slow when I'm aiming skillshots. Hard to explain but it makes it extremely difficult to play.

Also, I think because my mouse speed is out of whack, its making controlling the camera super difficult as well. If anyone might know how to fix this, please let me know. I'm considering just reinstalling League but that takes an hour+ and I really don't want to go through all that.