How to Modify the Slide Master in PowerPoint 2007
Open the View tab on the Ribbon and then click the Slide Master button, found in the Presentation Views group.
The Slide Master opens displaying placeholders for the slide title and body text. The Master can also contain background colors and other elements that are present on each slide.
The Slide Master includes placeholders for three objects that appear at the bottom of each slide: the Date area, Footer area, and Number area. A thumbnail of each Slide Master as well as the layouts for each Master are shown on the left side of the screen.