Export Invoices

From your control panel go to Orders > Invoices.

You can click the checkbox in the top left to select all invoices, all visible ones on the page or unselect all:

If you want to select individual invoices, simply check the box to the left of the invoice number within the invoice list.

Once you selected the invoices to be exported, click on the Bulk Actions button at the top of the list, and select from the Export options.