Amount to Pay field on Approve Invoice Page

Amount to Pay field shows the 'Shipment Amount'. Is there a way we can show the 'Invoice Amount' in the 'Amount to Pay' field.

Business Purpose: Users modify the invoice from amount A to amount B.

When user tries to approve the invoice, Amount to Pay field still shows Amount A and not B.So user needs to modify in Approve Invoice page as well to approve the right amount.

To avoid duplication, we would like the Invoice amount to be shown in Amount to Pay field.

Please advise.