You've come to the right person, vetsvs. I can help share the steps to enter the payroll for all of 2023 in QuickBooks Online.
The option to enter payroll information is only available for the current calendar year, and there are no paychecks created yet for the employee. Here are the steps:
Go to the Payroll menu and select Employees.
Choose the name of the employee, then Enter prior pay details.
Moreover, if you've already run payroll and need to enter prior payroll, you cannot do this directly in QuickBooks Online. Instead, you should contact the QuickBooks Payroll Support Team to help you add historical data to your payroll. They'll access your account and create an adjustment to record the old payroll transactions before using QuickBooks.