The Composition panel can show one, two, or
four views at a time. By default, viewer options (such as grids
and rulers) affect only the currently selected view.
To select a view layout, choose an option
from the Select View Layout menu at the bottom of the Composition
panel.
To scroll through view layouts, position the pointer
over the Select View Layout menu and spin the mouse wheel.
To apply view settings to all views in the current layout,
choose Share View Options from the Select View Layout menu. Hold
Ctrl (Windows) or Command (Mac OS) to momentarily reverse
this behavior.