Viewport configuration, which divides the working screen into sections, is displayed under the view menu. Which screen shape you want to work with in the viewport configuration dialog, that option is checked.
Location of the Viewport Configuration Command
You can access it under the Image tab Window title.
Viewport Configuration Dialog
Click the line View/Viewport Configuration in the classic menu. Click the View/Window/Viewport Configuration icon in the ribbon menu .
Select the screen you want to work with in the dialog that opens.
Click the OK button and close the dialog.