Changing an employee's job title doesn't update pay rates as a title change may not always result in rate adjustments. Only when you create a new employee and select a job title with rates already linked will pay rates be auto populated. Pay rates will also be updated if you update the rates in the job edit screen - you will see a note above of all employees that will be affected.

A simple rule: If the amount stays fixed from one period to the next: Quantity 1, if the amounts vary from one period to another, then quantity 0. For instance, salaries usually stay the same from one month to the next, so make the quantity 1. For overtime rates, those vary from one period to the next, so make the quantity 0.

Here we recommend in keeping the quantity 0 if the employee's income varies from one period to the next, make the rate the percentage: 7.5% would be a rate of 0.075 (7.5 / 100). Then when processing payslips for each period, the quantity can be updated to their income totals of which the contributions are based on.