To change the product type in your Cheese Master, click on the Product Selector located in the upper left or right part of the gear — depending on how it is oriented.
The default type is regular Cheese, but clicking on the icon will allow you to make Mozzarella, Feta Cheese or Goat Cheese.
Currently, the Cheese Master, the Dairy Expert, the Jam’r, the Smooth Juicer, the Oil Press, the Coffee Stand, the Weaver, the Winemaker, the Cool Packer, the Pie Machine — and the Brick Mill and Dutch Mill (from the Buildings tab) are able to make multiple types of produce.
The Ketchup Wiz, the Baker, the Brewery, and the Distillery only make one type of product. For now 🙂