Hello there, @dogdayscornwall.

I'm here to help fix the bank balance in your QuickBooks Online (QBO) account.

The QuickBooks balance is the total amount of all bank transactions you matched or added to the system. There are some factors that affect the balance of your bank accounts. These are the following:

• Outstanding transactions
• New transactions for a connected account
• Duplicate transactions
• Edited or deleted transactions
• Credit card (liability) account

To rectify the issue, I recommend checking out the transactions added in QuickBooks. Then, compare them to your bank statement. For more detailed steps, I suggest following the instructions under Step 4: Review any discrepancy reports from this article: Fix issues for accounts you've reconciled in the past in QuickBooks Online.

Once everything is corrected, you can now proceed with reconciling your account. Let me share this link for more insights into the process: Learn the reconcile workflow in QuickBooks. It provides information on how to edit a completed reconciliation.

Feel at ease to write a comment below if you have further concerns with reconciliation. You have my back to resolve this. Have a great day.