Currently the Order Summary can only be viewed in ascending order in the Salesforce app/Admin center (Configuration tool). There is no option to select/set this field to view orders in latest order - Descending order. This is not only a useful feature but a 'must have' feature.
CS agents working on tickets rely on the latest info to help their customers more efficiently - instead of time spent searching or toggling for the latest order.
Hope you can provide a solution for this request soon.