When editing a menu item you may edit the following under the Serving Options Tab:
Available Serving Option Categories - Drop down containing all of the serving option categories. Select a serving option category to display all serving options within that category.
Selected Serving Option Categories - Displays the serving option categories that contain serving options you have added to this menu item.
Serving Options - Select batch modifications to select which serving options you want to apply to a menu item.
Pricing Overrides - (This section is currently disabled. To add a pricing override to a serving option add it in the serving options section)