A User that has the Role of 'Driver' has the Home Terminal (HT) option set. The available HT list is populated by the Memberships assigned to the User.
To change a Driver's HT:
From the HT list select an Organization (OU)
To add a HT:
Add a Membership for another Organization (OU). The HT list will now have the option to select the newly added OU.
Note: if the OU you're looking for isn't available in the Membership list of Organizations, you can add a new OU by going to 'Management & Settings' > Organizations.