When you create or change a presentation in Microsoft Office PowerPoint 2010, the default font is Calibri. You can change the default font for new or existing presentations, and for presentations that are based on a design template.
To change the default fonts on a single slide, or to change the default fonts throughout your whole presentation, and for all new presentations that you create, use one of the following methods:
Method 1: Change the font on a specific slide
Method 2: Change the fonts throughout your presentation