Not sure what I've managed to do here, but when I click on the PDF symbol under "Invoice", I get an invoice but the filename is delivery.pdf - could be a bit confusing?
The odd thing is, when it attaches to an email (which is working now, many thanks for your help!) it is correctly numbered and named! Only when I try to download is it called Delivery.
Thought it might be a bug, so am raising it here!

Ruth