When you want your presentation to have more than one set of colors, fonts, and effects (like shadows, reflections, glows, and more), add another slide master with a different theme.
Your presentation currently has one slide master with a theme applied. To add a second theme, add another slide master with a different theme. Here's how:
On the View tab, pick Slide Master.
On the Slide Master tab, pick Insert Slide Master.
Tip: The second slide master inserts and is automatically selected.
On the Slide Master tab, pick Themes, and pick a theme from the list.
The Slide Master you've added will now have a different theme from the other Slide Master in your presentation.