Note: Viewport arrangements can be saved only in model space, but you can restore saved viewport arrangements either in model space, as model space viewports, or in paper space, as layout viewports.
In model space, click View tabViewports panelNamed. Find
In the Viewports dialog box, New Viewports tab, enter a name for the viewport configuration in the New Name box.
The name can be up to 255 characters long and contain letters, digits, the special characters dollar sign ($), hyphen (-), and underscore (_).