If a customer has a carrier account number established in the Customers screen, that account number should be visible -- and possibly also editable -- on the sales order screen and on the shipment screen. Salespeople and customer service reps sometimes need to confirm the carrier account number that will be charged at the time of order entry. The only way currently (2019 R1) to view that is to drill into the customer, and that is cumbersome.
In addition to the account number being displayed, it should also be editable on the fly. A customer may want different accounts charged in different circumstances, or may say "please charge this shipment to our account "XXXX" for a given order. Or they may not have an account stored in the customer file but may offer it for one-time use.