PowerPoint 2016: Applying Themes
This is an excellent video that provides additional background on how to apply a Slide Design Theme, how to customize the font, color, and size of your chosen Slide Design Theme. Please note that while customizing the Slide Design Theme to be careful of the color contrast between the chosen font color against its background color, in particular, observe the text readability at 2:36.
Having a sufficient color contrast is essential to creating effective learning environments. There will be further discussion on color contrast farther into the course.