There are two options for changing a redemption rate for a customer,First option would be giving that customer a special rate or the other or the next option would be

At the Home Screen you want to Select number two, like the photo below, And Type in the loan that you are wanting to reverse back to a loan and

Select The Loans to Retail on the Main Menu Screen, Then Select wether you would like to do all Overdue loans, Due Date Range or Loan No. and Click the