You can completely replace a font with a different font in your presentation. You might do so for design purposes (because one font looks better than another) or due to a font being unavailable on your system.
Choose the ribbon command Design | group Design | Replace font 
to replace the font of the entire presentation. The following dialog box appears:
There are two dropdown lists in the dialog box. In the top list, you select the font that you want to replace and, in the bottom list, you specify the replacement font.
As soon as you confirm with OK, Presentations replaces all instances of this font throughout the presentation.