I have a screengui im trying to sync [closed[
This isn't really a scripting questions, but you should use offset instead of the scale property.
Offset uses the % of your screen. So something that is 100% (1 offset) means that it fits the whole screen always. so 1 offset x and 1 offset y should fit the whole screen.
More information: https://www.robloxdev.com/articles/Intro-to-GUIs