In the Item Record > Purchasing/Inventory tab > Locations subtab > Preferred Location field, users can set the location that they want to default on the Sales Order line when the item is added to an order.

However, there might be a scenario that this location is not being automatically set on the Sales Order line
Aside from scripts, the possible reason why the Item’s preferred location is not auto populating in the Sales Order is because the Store Pickup feature is enabled on the account. The Store Pickup feature is not compatible to setting of preferred location on Sales Order item line
To disable the feature:
- Navigate to Setup > Company > Enable Features
- Click on Transaction tab > Shipping & Receiving subtab > Uncheck Store Pickup
- Click Save > A message pops up “You are about to disable the Store Pickup feature. Doing so will disable the Store Pickup fulfillment workflow. Do you want to continue?” > Click Ok
Important Note: Please discuss with your team before enabling/disabling any settings or preference including this one.
To test the behavior:
- Create a new Sales Order
- Enter any Customer
- Enter an Item
- Preferred Location should be assigned to the Sales Order line