You can change the font and size of every text element on your BookPoints site, including the site name and slogan in the header, individual page titles, and ordinary paragraph text.  Click Setup Menu > Design Customization to access the design options screen.  Scroll to the Extensions section and select the Font tab.  You can replace the BookPoints custom font stack with your own custom stack or use a Google Web Font (see on-screen documentation).  Don't forget to click the Save configuration button at the bottom of the screen to save your changes.