I'm here to ensure you can update the bank account of your expense transaction. This way, you'll be able to transfer the transaction to the correct account and continue with your reconciliation.
Let's go to your newly added bank account in your Chart of Accounts to correct the entry. Here's how:
Go to the Accounting menu.
Select Chart of Accounts.
Locate the new bank account, then select View register under the Action column.
Find and select the expense entry.
Choose the right account in the Payment account field.
Click Save and close.
I've attached screenshots below that shows the fourth to seventh steps.
Once done, you can now continue reconciling your account. I'd recommend performing it every month to easily detect errors and keep your books accurate. For the detailed steps, kindly refer to this article: Reconcile an account in QuickBooks Online. It also contains information on how to edit completed reconciliations.
Please let me know if you have other concerns. I'm just around to help.