The initial values on a payrun come from the defaults for the employee, but you can edit them on an individual payrun.
Any changes you make here will affect just this payrun.
Click "Payroll" in the main menu. If you haven't already started the payrun then do so by following the on-screen instructions.
You'll see a list of all employees included on the payrun. You can click on any entry in the list to edit it.
Clicking on the first line will allow you to edit the basic pay amount. Alternatively you can click the 'Edit Regular Pay' button at the bottom of the window.
Clicking an existing addition/deduction or the relevant button at the bottom of the page will allow you to make changes, using any Pay Codes you've created
You cannot edit the tax, NI and other auto calculated fields. Any lines related to pensions, student loans, etc are calculated based on the settings for the employee
As you make changes you'll see that the auto-calculated lines are automatically updated for you.
Once the entry is set up how you want to to be you can close the window.