An employee was promoted but we did not change the QB account the pay comes from. How do I change the previous paychecks to be charge to the correct QB account?

Hello there, @Gary10.

There are two ways on how how to change the previous paychecks to the correct account in QuickBooks.

The first one is to delete and recreate the paycheck using the exact information. You can also take a screenshot for visual reference.

To delete a paycheck, here's how:

1. Click the Workers tab from the left menu.
2. Select Employees list.
3. Under Run Payroll, select Paycheck List.
4. Change the date range if necessary, and then select the paycheck you want to delete.
5. Click Delete.
6. Mark the tick box to confirm the deletion, and then click Delete Paycheck.

Recreate paychecks:

1. Sign in to QuickBooks Online.
2. Go to Workers and select Employees.
3. Select Run Payroll.
4. Choose the employees you'd like to pay then enter the hours and memos based on the deleted ones.
5. Select Preview payroll.
6. Click Preview payroll details or Submit payroll.
7. Hit Finish Payroll to complete the process.

The second one is creating a journal entry. This way, you can use them to reconcile the account. You can either combine all of the employees' paycheck totals into one journal entry or create a separate entry for each employee. To ensure the amounts are accurate, you can run a payroll report (Payroll Summary, Payroll Summary by Employee, or Payroll Details) for reference.  

For more details about how to enter the debits and credits for wages and taxes, as well as a sample paycheck, please check the following article: Manually enter payroll paychecks in QuickBooks Online.

I also recommend consulting an accountant on what specific accounts to use recording the transaction to ensure the accuracy of your books

I've added our Payroll and workers page it provides helpful articles that might help you in managing your QuickBooks account.

Keep me posted if you have additional questions. I'd be happy to answer them for you. Wishing you and your business continued success.