Me and my friend are making a game together, and on his screen all the gui is positioned differently than how its positioned on my screen. Why?
How can I make the gui positioned correctly, or atleast look not ugly
This is because your GUIs are scaled and positioned with offset, and not scale. Basically offset just moves/scales something by however many pixels. Scale is a percentage of your screen size. There are a few plugins made for converting offset to scale.
it is most likely different screen size (like 4k 1080p you know), there are plugins made to help with this like https://devforum.roblox.com/t/plugin-autoscale-lite-for-guis-scale-your-ui/217704