Go to Forms -> Settings -> Better Address and select which locales to enable. Click the Update Settings button.
Now on any Gravity Form (new or existing) you will be able to choose which locale to be the default for the address field, and optionally which state to make the default.
For example, if you enabled Swiss Cantons in the settings interface, it would be among the Address Types you can choose from when adding an address field.
Note also that the Zip/Postal Code label changes appropriately.