About changing the background
You can change the background color or background design on slides, notes, and handouts. Changing the background is useful if you just want a simple shade or texture for a slide background and not all the other design elements in a design template. Or, you might want to change the background to emphasize sections of a presentation. Besides changing the color, you can add shading, a pattern, a texture, or a picture.
When you change the slide background, you can apply the change to the current slide or all slides. For notes, you can change the current notes page or all notes pages. When you change the background for handouts, it applies to all pages as well as the printed outline.