When to turn off personal time accrual
If you have set up an employee for personal time to accrue each payroll, and have a payroll where you do not want to add to employee accruals, check the box "Turn Off Personal Time Accrual" in the Payroll Information screen. A good example for when you might need this feature is when running a bonus payroll.
Personal time to accrue per payroll
To see if an employee is setup to accrue/earn time per payroll, go to Payroll → Employees → (find the employee), click on the personal tab and see if the box "Earn Per Payroll" is checked: