Controller - keyboard & mouse glitching

I just got a controller to use on my PC and when I opened a game when I walked forward or backward it would also move up and down on the command menu (the game was kingdom hearts) I thought it was weird so I went into an FPS (apex legends) and noticed the game jittering back and forth from mouse to controller, when I went into a game A on the controller would open chat bar (in-game) and when I aimed my sensitivity would increase 10 fold.

I then searched YouTube for an answer and only got led to steam and messing around in big picture mode, mind you neither game was through steam but the official EA launcher and epic games respectively, While looking at YouTube and my big picture mode they didn't look the same (probably an update) and I couldn't locate the settings they changed. (which I don't even know if that will fix my problem)

I also tried unplugging my keyboard & mouse and only using controller and same thing although it stopped the jittering back in forth. this is as far as I've gone before I got annoyed and decided to ask my question in somewhere where I'd get a specific answer

:)