lock entered amount field after saving the receipt in AR module

We need to implement a control in Oracle Receivables to prevent modifications to the 'Entered Amount' field after a receipt has been saved. Currently, users can edit this field even after the receipt is saved, which poses an error. This constitutes a critical error in our financial processes.

The desired behavior is as follows:

During Receipt Creation: The 'Entered Amount' field should be editable, allowing users to enter the correct amount.
After Receipt Save: Once the receipt is saved, the 'Entered Amount' field should become read-only, preventing any further changes.
The current behavior, where the 'Entered Amount' remains editable after save, is a critical error because it directly impacts the integrity of our financial data.