Hello there, theopoldinen-gma.
If you mistakenly entered a date on a transaction that's already reconciled, you can directly edit it. Let me show you how:
- Go to the Gear icon and click Chart of Accounts.
- Look for the account and click View register.
- Locate the transaction and select it. Then, Edit.
- Change the date and click Save and close.
- Confirm the message prompts.
On the other hand, if you're referring to the mistakenly entered Ending date, you'll have to undo the reconciliation on each transaction. Then, reconcile it again with the correct ending date. For more details, you can check this article: Undo and remove transactions from reconciliations in QuickBooks Online.
Feel free to post your questions here if you have other questions or you're referring to something else. Take care!