when me and my friend went to play we tried to play just any random match/ server but im getting this horrible aim locking thing where the dpi changed at anytime it could feel super slow or super fast like its switching from .1 all the way up to like 20-25 (in the in game mouse sensitivity) and the game takes control of the mic when u launch it (idk why this is) and the custom classes were glitching out when i create one it wouldn't save
This issue (with the sensitivity), in my experience, tends to happen when your mouse's polling rate is really high (for CoD anyway). I used to have it on 1000hz and got the same glitch but at 125hz it works perfectly fine. Changing it depends on your mouse's software but there are some programs out there that allow you to change it for any mouse.
Here's a good website to check your polling rate quickly, just click and move your mouse really fast back and forth: