You can set the resolution for all items in a layout by right-clicking anywhere on the Viewing Grid, and using Resolution from the context menu to select from the available options (Auto, High, or Low). Auto allows each device to display at it's own default setting. Once the resolution for an entire layout is set, you can still set the resolution of an individual item as desired, in which case the layout resolution will display Custom to indicate that not all items are using the same resolution setting.