As a Page Manager: 
  1. Navigate to School Website > Website Management > Websites >... > Edit Website
  2. Click Master Layouts.
  3. Select the desired Master Layout.
  4. Select the Styles tab in the upper left corner. 
  5. At the bottom of the window, click Edit Styles and select Regions.
  6. Click the region and use the style drop down in the upper left to select the style.
  7. When satisfied with the changes, click 'Apply Changes'.