Hi jacques-tessier.
Mistakes happen and sometimes aren't always noticed but that's why QuickBooks Online lets you pull up and edit transactions quickly. I'd be happy to help you get back to business with getting this transaction corrected.
It sounds like you have a closing date set up in your QuickBooks Online. A closing date is a lock to prevent changes being made after a certain date to prevent issues with the accounts. I recommend reaching out to your accountant or whoever set up the closing date to prevent any negative impacts on your books. In order to remove the closing date you'll need to go to: Gear>Accounts and Settings>Advanced>Accounting. This'll allow you to toggle the closed books as off. Once that's done you can edit your transactions without it asking for a password.
If you have any questions let us know and we'd be happy to help.
