Hey Wayne,
If the customer specified Fixed Freight on the Costs tile of the item record that was created for Freight, and also selects checkbox "Include Item Fixed Charge", then Standard ERP automatically knows to look at the Freight/Delivery Accruals account specified in
Module Inventory >> Settings >> Account Usage Inventory >> Purchase Cost tile >> Freight Accrual
because this is the account system uses to book the cost of freight on receipt of goods.
Hope this helps to clarify what triggered the system to display that message. If you have any further questions, please let me know. Thanks!
Best Regards,
Omar