I can provide information on how to change Payroll Service key in QuickBooks Desktop.
To start with, remove the payroll service key from the client’s subscription. Here's what you'll need to do:
Click Employees from the top menu.
Select My Payroll Service, then click Manage Service Key.
Click the Service Name.
Click the Remove button, then select Yes.
Once done, you can now enter service key from your subscription. To do this task, here's how:
Click Employees from the menu.
Click Payroll, and choose Enter Service Key.
If you have an existing payroll subscription, you are prompted to specify if you want to add this file to your payroll subscription. Choose Skip to go to the Service Key window, or Add File to add this file to an existing Payroll subscription.
Enter the service key, then select Next. A confirmation message appears.