After you have approved an invoice, you can find and track them. 

Note:  If a delegate has approved the invoice on your behalf, as a manager you can also view these invoices in Spend > Approvals > Search.

View approved invoices in web app

In the web app, go to Spend > Approvals > Search and click the Invoices tab.

Here you can find all invoices that you have approved. In addition, you can track them along their approval process.

View approved invoices in mobile app

In the mobile app, go to Spend > Approvals, and tap the Invoices tab. Next, tap the Status filter in the top left corner and select Approved. Now, you can see all invoices that you have approved. In addition, you can track them along their approval process until they‘re exported.