The main and secondary preferred wholesaler configurations are in Shop Configuration. 

To set your preferred wholesalers:

From the Minfos Launch Pad:

1. Click the Special menu and select Utilities.

2. Click the Config menu and select 1. Shop Configuration.

3. Select the General tab in the Shop Configuration window.

4. Enter the wholesaler codes into the Main Wholesaler and Second Wholesaler fields.

5. Click OK to save.

Watch the video below to learn how to use Product Quick Fix to update the Preferred Supplier against stock cards