I have already begun re-reconciling 9 months of statements.  Your suggestion to invite an accountant makes no sense.  I am a finance manager and not ignorant of how to un-do previous reconciliations.  Furthermore, your other instructions really make no sense, as you are pointing me to a link for further information that references QB Online, and I am on Enterprise Desktop.  I am doing this the right way, although it is not fun, and at least I know that when I'm done I will have fixed my error.