If you are left with black bars, then you are using the "Letterbox scale" mode.
This mode is optimal for beginners.
To take up the whole screen, you need to do more actions.
Select the "Scale inner" mode and set the positions of the control buttons when you start the layout.
This can be done with the command
"System On start of layout ->key Set Y to ViewportTop(0)+50
"
Or Anchor behavior.