If you are unable to see PO's, it might be you do not have all the Purchasing Defaults needed to view those. I recommend navigating to Purchasing --> Reference Tables --> Purchasing Defaults --> enter your User ID and click 'Find', you should be able to see all the Approval and Ship Codes that are assigned to you. Also, there might be a few codes that are not assigned to you.
Once those codes are assigned to yourself you should be able to view the PO's. To do so, select the code you want and drag it into the Assigned column.