I want to route you to our QuickBooks Support team to handle this type of concern.
In QuickBooks, entering your employee's profile will based on the employee's W4 to ensure the taxes are correct as well as when you already created paychecks.
Additionally, regarding entering employees' PO Box addresses, please know that only our Support Team can add them. This is to ensure the right address will be entered.
Here's how:
Sign in to your QuickBooks Online (QBO) account.
Click the Help button.
In the QuickBooks Assistance chatbox, select Talk to a human and choose I still need a human.