I have an admin user (not super admin) and he is unable to change a product for a user which is subscribed. If you goto Browse Users -> Payments -> Click on the first invoice -> Click on the [X] button... I get a popup which says: "You have no permissions to perform requested operation. Please contact webmaster: ..." However this admin user has all of the permissions checked off. Why can he not use the "replace product" feature?
Please contact us in helpdesk and ask to provide latest /amember/application/default/controller/AdminUserPaymentsController.php Also, fix will be included in next version.