Welcome and thanks for dropping by the Community, @ceilings-potch.
The ability to edit the delivery note in QuickBooks Online (QBO) is currently unavailable. I can see how having this option would be helpful for you and your business. Rest assured I'll pass along your suggestion to our Product Developers. They're always looking for ideas to consider on how to improve QBO.
In the meantime, I recommend visiting our Blog site. This is where we share recent happenings and future developments, such as updates to newly added features.
Just in case, I'll add this article for future reference: Create and print a delivery note.
Please know that I'm only a post away if you have any other questions or concerns. I'll be here to help. Have a wonderful day!