So i was making a main menu and when I brought up the output a bit up this happened.
As you can see the button becomes bigger and smaller.
Before it was like this -
I don’t know what happened but here are the properties of the TextButton -
Also these two buttons have UI corner inside them.
Could this be a bug of UI corner? 
You made the output bigger, just make it smaller
Make Output size less. It take more than half the screen and the main game screen will be smaller.
That is not an error, whenever you change the size of anything on your screen the UI will automatically scale it so that everything fits in the screen. Hope that helped 
Have a good day!
@Devolas @StodiusDev @Omb2a you may have tried to help but this isn’t the problem.
I have edited the post with more images.
Now you can understand that the button’s size become bigger/smaller on each device.
Try enabling TextScaled in the TextButton.
My TextScaled is already enabled.
Add a “UiAspectRationConstraint” to your primary frame then the children of that frame that have children inside them.
I noticed that this only occurs when I make my UICorner’s CornerRadius to 1,0
Yep it’s now alright thanks
Have a nice day 
Change the property of the Text to ‘TextScaled’.
