EDIT allows you to select “Accounts Receivable”, that then creates a new field which allows you to select a “Customer”, that then creates a new field which allows you to select an open “Invoice” from a drop down list.
This is done from the imported bank statement transaction “EDIT”. No need to go to Sales Invoices or Customers as any entry there would only duplicate the imported bank statement transaction as you noted. The link you provided dated 2015 regarding using Customer Credits is now a redundant process