Team members cannot edit pending requests
Create a PO with any details and send it for approval. navigate to the newly created Purchase Request and select the 'Actions' drop-down. The Approver should be able to 'Edit' the Pending Request whether or not the setting "Allow users to edit approved /not paid POs" is on or off.
Team members should be able to edit pending requests when the "Allow users to edit approved /not paid POs" is on.