The initial values on a pay run come from the defaults for the employee, but you can edit them on an individual pay run.
Any changes you make here will affect just this pay run.
Click "Payroll" in the main menu. If you haven't already started the pay run then do so by following the on-screen instructions.
You'll see a list of all employees included on the pay run. 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.