You can get a copy of your invoices by opening it using the customer Transactions List page or Audit Log report. If you want to share an invoice you can email it to your customers.
To run the Audit log report, you can follow these steps:
Go to the Gear icon.
Select Audit log.
Use the Filter option to easily locate the invoice.
Click Apply.
To know more about how to handle customer transactions, you can use these references: