For a new user (who is not a System Administrator) to see the transactions in your ePayment Center , they will need to be added to a back-end group that has permissions to both the ePayment Center and the that the submissions are coming from. This is usually the Form Center or the Forms . If the user does not have permission to view the submissions, they will be unable to see the associated transactions.
For example, if you have a user who needs permission to see transactions but doesn't want to change anything on your forms, you can give them group owner-level permission to the ePayment Center but only author-level permission to the categories in the Forms and Form Center that they will need to see.