To view a customer's statement, go to the customer's page, click Sales orders & credit notes, and click the smaller Actions dropdown button under the Unallocated account payments/credits section, where you'll find the View account statement button.

From there, if you go to the print preview of the page (File -> Print, or Ctrl / Cmd + P), and change the destination to Save as PDF, you can save it in a more sendable format.