Many fields (such as Vehicle Colour or Payments Method) in the diary have preset values, which you can edit in the Edit List page. If the field's list can be edited, you will see an additional button next to it, which will bring you to the Edit List page.
To lock the list, go to Settings, then Application Options and clear 'Allow new strings in Pickup Lists'.
To reset to factory settings, go to Settings, then Application Options and select 'Reset pickup lists on start-up', then restart ADI-diary.
See also: Application Options