Method

One reference, carried through

The fix for documents that disagree is boring and completely effective: give the job a reference and put it on all four.

Any string works as long as it is yours and it never repeats. A date and a client initial is enough for most people. Put it in the reference field of the quote, keep it on the order, repeat it on the invoice and the receipt.

Why it pays off later

Not while the job is running — you remember everything for about three weeks. It pays off in March, when a client queries an invoice from November and the only way back to what was agreed is a shared reference.

The other half

Export each document as a PDF and keep it. A template you filled in and never exported is a document that existed only in a browser tab.