When an AP voucher ( or grant voucher) is created, at least two records are created:
The voucher header   - contains information about the payee, the voucher description, batch and the various dates. 
One or more voucher line items - contains the line amounts, descriptions and account numbers.

When you change items on the open item tab such as the payee name or address, that information is saved on the voucher header record. 

Thus any reporting you do on the voucher will use the most recent values. 

If you are creating a voucher that will be paying many different vendors ( perhaps a project grant), the information on the various amounts paid and to whom they were paid is not maintained on the voucher.  Only the final payee name and address is saved.  The payee name associated with each payment is found on the check record.  The address information is found in the data export that is created during the printing of the checks ( assuming you create an export) and is now also stored in the payment record in the appayheader table.