To select default accounts for Payroll within KeyPay (the Employees tab in QuickBooks):
Go to Employees, and then Payroll Settings
Click on Chart of Accounts under the Business Settings column
You will then be presented with 4 categories of accounts that you can customise as default: Default Accounts, Pay Categories, Deduction Categories and Expense Categories.
Click into any category to view what is currently default and what accounts you can change it to.