My Payroll was pulling from a "fake" checking, I fixed it but now I need to go back to previous mths and change the account. How do I do that?

Let me help you with changing your account in QuickBooks Online (QBO), tdt1515.

We’ll have to open the Chart of Account from there and then, edit the transactions recorded. I’ll be your guide today on how to perform these steps.

1. Go to the Accounting menu.
2. Select Chart of Accounts.

3. Locate the Fake account transaction.

4. Click the Run report drop-down list under the Action column.
5. Select Edit. 
6. Hit Save and Close. 

I’ve also added this article to learn more about the Chart of Accounts. It contains details to help them be more organized and accurate.

Please let me know if I can be of any additional help. Stay safe and enjoy the rest of the week!