Keynote

Highlight text in Keynote on Mac
You can highlight text in text boxes and in shapes. These highlights aren’t visible in printed presentations.
When multiple people are working on a presentation, each person’s highlights appear in a unique color. To learn how to change your color, see Set author name and comment color.
Tip: If you want highlights that are visible in your final presentation, add a background color to text in any color. This type of highlight isn’t included with Keynote review tools.