Click the row action button against any invoice row, and these options are shown:
Share - Share the invoice document to the project portal to be viewed by the cc'd contacts. The person marked as the attention to contact on the invoice will be automatically included in the invoice share.
Download - A copy of the current file version will be downloaded to your device.
Open invoice - The invoice or credit note shown will open. Use that page to download previous document versions, view the full invoice / credit details on screen, and more.
Manage shares - Use this option to see who the invoice document has already been shared with, and cancel any existing shares if required.
Learn more about creating invoices and credit notes.