Payroll has created an account just called 'bank' but it comes out of my linked account. Why has it been separated and how do it combine the accounts?

Hello there, dustydan1984-gma.

I'm here to share some insights about merging accounts in QuickBooks Online.

Accounts are permanently combined after the merging process. It can't be undone and is irreversible. Additionally, once you merge two accounts, QuickBooks moves past transactions from one account to the other. This must be the cause of the discrepancy that is now showing in the account. 

You can use this article to learn how you can fix issues for accounts you've reconciled in the past in QuickBooks Online.

I've also added this resource if you're unfamiliar to the whole reconciliation process: Learn the reconcile workflow in QuickBooks.

If you need any additional help or have any inquiries about the accounts in QuickBooks, please don't hesitate to tag me in your comments. Enjoy a wonderful day!