Single Store to Process (Default Store) - System Option

>Utilities>System Options>System Wide>General>

Category Configuration

Type- Can be Global, Assigned or User 

When you have more than one store code in RFMS and your users need different default stores, click the select button for the store code this user will use as its default store.  

To set the stores available for this user go to Order Stores Visible to User

There is a separate option for the default store in Sales Floor Assistant- Single Store to Process.