You can set a preferred contact in two ways.
Start by going to your Address Book, and clicking a subbie’s company from your list.
In the slideout that appears from the right, look at the Contacts table at the bottom. Then you have two options:
Option 1: Add a new preferred contact to a company
Click the ’+ Add Contact’ button.
Fill in the contact details, and tick ’Set this person as a preferred contact’ before you click ’Add Contact’ at the bottom.
Option 2: Set (or unset) an existing person as a preferred contact
Still in the subbie's company slideout, click the three dots menu icon for a person in the Contacts table.
Choose ’Set preferred contact’ from the menu that appears.
If you change your mind later, this menu option becomes ’Unset preferred contact’.