When you have a PowerPoint file with a lot of slides, don’t format them individually. It’s time consuming, and too easy to apply formatting inconsistently. Instead, format the slide masters, and the masters will apply the formatting to the individual files.
This tutorial works in any version of PowerPoint, and on both Windows and Mac. The full article, practice file and screencast is available for free on TutsPlus. Or you can watch just the screencast here: