What am i trying to do
Make my game UI better, by changing their sizes, etc.
Problem
I changed the ZIndex for my items to 5-100 and it seems like the mobile joystick disappears.
My attempts to solve the problem
None. I know this may see vague. But i'm working just with a GUI and i don't find enough information about it with ZIndex.
Question
Is there any way of fixing this? And if there is then how?
ScreenGui's have a DisplayOrder property which is what you are looking for:
https://developer.roblox.com/en-us/api-reference/property/ScreenGui/DisplayOrder
When Roblox creates it's mobile UI, it creates a ScreenGui under PlayerGui called "TouchGui", which defaults to having a DisplayOrder of 0. So you will either need to set your UI to have a lower DisplayOrder than 0, or at runtime you can find the TouchGui and set it's DisplayOrder to be higher than your UI DisplayOrder.