Each slide can be displayed using three planes:
Background: To change the background, just right-click on the slide and choose Edit background.
When you change the background of a slide, the changes will be applied to all other slides in the project.
The ‘Show background’ option can then be manually disabled on slides where you want a different background.
Overlay: To modify the foreground, simply right-click on the slide and choose « Edit overlay ».
When you change the overlay of a slide, the changes will be applied to all other slides in the project.
The ‘Draw overlay’ option can then be manually disabled on slides where you don’t want an overlay.
Using the foreground and background helps standardize slides quickly. For example, always have your logo in the same place, or display the date and time in the same place without forgetting to apply it on a slide.
The third plane is actually the slide itself. To modify this plane, simply select the slide using the left mouse button. When you edit a slide, the changes are applied only to that slide.