DisplayTgls > Object Toggles

Choose All windows or Current window. Current window will only change the display state of the active view.

Choose one of the following:

Keep current setting: do not affect the current canvas display setting for this view.
Display at all view angles: the canvas should be always visible.
Display only when perpendicular: this is the typical use of overlay planes, but can also be used with other planes. You'll find it useful if you have a series of canvas planes for a presentation, and want to display them sequentially. Click through each image plane, using the "Look at" icon in the Plane/Layer editor to create a dynamic presentation.

DisplayTgls > Object Toggles > Canvas planes