Existing invoices still show the old Primary Contact even if the Primary contact has been updated on the customer record. You can do the steps below if you would like to print existing invoices with the updated Primary contact on the Bill To field:
1. Navigate to Transactions > Sales > Create Invoices > List.
2. Click Edit next to the Invoice.
3. Remove customer name on the Customer: Job field.
4. Select the customer name again on the Customer: Job field.
5. Click Save.
6. Click Print icon on the Invoice.