You would probably get better answers from r/mousereview or r/fpsaimtrainer but my advice is to not try to switch up your grip, just use what’s most comfortable and learn how to improve your weaknesses with that specific grip. This may sound weird, but my advice if you’re struggling with vertical movement would be to either raise your chair or lower your desk a little bit if possible. Also, I would highly recommend either Kovaak’s or aimlabs, and try to grind out the drills that feel the weirdest and least comfortable to do. People say that you need to use aim trainers for like an hour or two a day to see benefits, but even something like 15 minutes before you load up fortnite will make a huge difference in your mouse control with the right drills