If you change the supplier of an invoice in Verify, and there is an invoice definition associated with that supplier, you can choose to have Verify reinterpret those invoices. To do this, select in the Verify job description Control settings or (if you are using an inbox) in the dialog.
Reinterpretation is also performed if the supplier is changed in the invoice definition (most commonly during optimization) after one or more invoices were interpreted. This can happen if you interpret several invoices of the same type without verifying them. The invoice definition does not have to be complete for an invoice to be reinterpreted.
Note: There is a related setting in Eiglobal.ini, namely CopyOldValuesWhenReInterpret.
The Verify module: An overview