Enable the Revenue_Ext audit table.

1. Go to Administration > Audit tables
2. Locate the table called Revenue_ext
3. Select this row and choose Enable
From this point forward changes to the Appeal field on payments will be shown in the Audit report and on the Revenue history report.

Note: Enabling Audit tables for revenue can increase the database size.  It's recommended that audit data is periodically purged. See this document regarding database growth management.