On either of the Apps, on the 'Home' page, click on 'Existing Certificates & Drafts', then on the Certificate you would like to see.
Any Certificates which are in Red are Drafts and can be updated.
Any Certificates in Black have been issued and you can click to download and view them.
If you have a lot of them, it may be easier to go to the customer or job address, and from there select View Existing Documents and Drafts.
The Existing Certificates and Drafts list is just that - a list. To view older records you will need to tap the Download All' button at the bottom of the screen.
This list is approximately 2 weeks worth of records, so if you need to view a very old record, you may need to tap several times.