How can I change the pay period from sun-sat to mon-sun??

I'll be happy to guide you in changing your pay period. 

To begin with, please know that we can't edit a pay period once you've created the paycheck. However, if you haven't made the payroll or paycheck yet, here's how we can edit it: 

If you have QuickBooks Online Payroll Enhanced:

1. Go to the Gear icon and select Payroll Settings.
2. Proceed to the Payroll and Services section, then choose Pay Schedules.
3. Select Edit next to the pay schedule you want to edit.
4. Update the pay schedule's info and click OK.

If you're using QuickBooks Online Payroll  Full Service, Core, Premium, or Elite:

1. Go to the Payroll menu and proceed to the Employees tab.
2. Select the employee's name.
3. Click Edit Employee.
4. Click the drop-down list for How often do you pay [employee]? Then, select the pay schedule for the employee moving forward. Or, to create a new pay schedule, select Add new and fill out the appropriate fields.
5. Click OK, then select Done.

For further reference on managing your payroll schedule, please refer to this article: Set up and manage payroll schedules.

If you need to print paychecks, this article can guide you: Print or reprint paychecks and pay stubs.

Let me know if you need further assistance changing your pay period or have any QuickBooks-related concerns. Keep safe.