How can I set up default paragraph styles and fonts in Encore?

Customizing all pages can easily be done by going to Book Settings > Customize Page Properties

Customize the styles and fonts by clicking on the Properties menu located on the right of the page display.
Select the specific paragraph style you want to customize, then choose the font family, font style, and size. Use this tool to determine all paragraph styles for the yearbook: headline, subhead, body copy, caption and photo credit.