Hello Everyone!
i was recently trying to make my UI for one of my games but i was thinking why is it glitching out on mobile and other devices but then i found out ROBLOX does NOT help you with that.
i first tried using a plugin called Autoscale lite because i used it before but it seems it does not work now 
how can i fix my UI?
Hi! I had already got stuck in this same point, and I discovered some ways you can do that!
If u want the UI object stay the same size in pixels on all devices, you need to use offset size, that is the amount of pixels.
Else, if you want to make the UI object adjust the percentage size to each screen, you need to use scale. This will make both, X and Y scale change, adjusting to screen percentage, but if you want to make the shape of the object stay the same, you can use UIAspectRatioConstraint. You will need to add the UIAspectRatioConstraint object inside the UI object you want to auto-size. You can control the DominantAxis, and AspectRatio, controlling the object shape, and size at the same time.
Here is the Roblox documentation: https://create.roblox.com/docs/reference/engine/classes/UIAspectRatioConstraint
sorry but im a bit confused
Watch this video, I hope it helps! https://www.youtube.com/watch?v=K4ystD3ZOLU
thank you ill watch this! :D!
hope i fix this
Sorry, I send the wrong video, click the url again, now its the correct one!
Theres no way for ROBLOX to help, they already provide the most simple UI editor ever.
Just read through the full User Interface documentation.