Cameras provide video in a variety of aspect ratio formats. To populate layouts efficiently, DW Spectrum attempts to match the default aspect ratio of an Item window to the aspect ratio of its contents.
The Viewing Grid adjusts to the aspect ratio of the first item added. To change the aspect ratio of an entire layout, right-click anywhere on the Viewing Grid, and use Cell Aspect Ratio from the context menu to select from the available options (4:3, 16:9, 1:1, 3:4, or 9:16).