On the View Menu, click Change Pane Orientation, or click the 
button on the toolbar.
Toggles the viewing areas between Side-by-Side Format, Upper-Lower Format, and Full Screen Format (Shortcut F).
See also
On the View Menu, click Change Pane Orientation, or click the button on the toolbar.
Toggles the viewing areas between Side-by-Side Format, Upper-Lower Format, and Full Screen Format (Shortcut F).