As you might remember, you can randomly choose a text combination, or you can click on the small icon next to the Text Option and define one on your own.
To define the fonts for the presentation, you have to scroll down in the Text Configuration Menu and find the small pencil icon on the Template Style.
In this new menu, you can name the Fonts Configuration; this way, it will be saved in your Prezi account, and you will be able to use it on other presentations.
You can then select a font for your titles, subtitles, and body of your presentation.
Remember
If you can’t find the font you want to work with or the font defined in your company’s brand book, you can add the font from Google Fonts directly in Prezi.