Changes to the receipt configurations (regarding Prefix, Number of Digits, and Suffix) are only available when the receipt is initially created. These changes can be made by following the steps below:
  1. Go to Setup > Select Receipt Manager
  2. Click Edit next to your Receipt Template
  3. This will land you on step 1. Identify Template
However, once any receipts have been generated, those fields are greyed out and can no longer be edited. If you would like to change these fields, then a new Receipt Template would have to be created.