Every site has a default placement. Then when an item is added to an agreement it is automatically allocated to this default

To change a sites default placement

1. From the home page choose Sales, and Customers
2. Choose the Site Delivery tab
3. Choose the Placements tab
4. The current default placement is shown by a single tick in the Default Placement column
5. Select the placement to mark as being the new default
6. Choose Make Default
7. The tab is refreshed and your selected placement has been marked as the default for this site