We also save our documents as PDFs and this default behavior is inconvenient. QB desktop saves documents as "Invoice XX" or "Purchase Order XX". So I don't know why QBO wouldn't do it the same way. It would be great if we could customize it by pulling data from the document, such as "Invoice XX - Customer - Customer PO.pdf" or "Purchase Order XX - Vendor - Date.pdf", etc. But at the very least it should behave the way desktop does.