In the pane on the right of the QuickBooks tab, there is a menu to switch between viewing invoices and estimates for a customer. You can also download the invoice or estimate as a PDF over the Button or open it in a browser with the Button.
Above the customer information on the left, you can select between the contact and the linked company.Related articles:
How do I setup the Finance Connector for use with Quickbooks?
How to transfer contacts to QuickBooks using the FinanceConnector