Can I change a bank recon statement ending balance.... Already recond but the amount of the statement ending balance was incorrect ?

I've got your back in reconciling your bank account in QuickBooks Online (QBO), @print3.

When you reconcile an account, you compare transactions in QuickBooks with the same ones on your bank statements. Yes, you can change a bank reconciliation ending balance if you unintentionally entered it incorrectly at the start of the process. To do this, here's how:

1. While you're reconciling an account, in the Reconciliation window, select Edit info. 
2. Review the Ending balance and Ending date.
3. Check your bank statement. Make edits as needed.
4. When you're done, select Save. 

To learn more on what to do when QBO doesn't match your bank statement at the end of reconciliation, I'd recommend checking out this article for the recommended fix: Fix issues at the end of reconciliation in QuickBooks Online.

Also, I'd recommend reconciling your account every month. This way, you can effectively monitor your income and expenses and detect any possible errors accordingly. When you need help doing or fixing a reconciliation, you can use this guide: Learn the reconcile workflow in QuickBooks.

Keep me posted on how it goes. If you have other banking and reconciliation concerns, please don't hesitate to comment below. I'm just around to help. Take care, and wishing you continued success.