The Default button allows you to update the default settings to several of the Part/Machine tab's options on the Setup Options dialog box (Edit | Preferences | Setup). When you create a new measurement routine, it reflects any changes made to the accessible parameters, only if you click the Default button. If you click the OK button (without clicking the Default button) the defined parameters will only apply to the active measurement routine and will not affect PC-DMIS's entries. The default values are stored in a JSON file. You can update these parameters in the appropriate dialog box or you can use the PC-DMIS Settings Editor application. See the "Modifying Setting Entries" chapter.
If you change any of the parameters and you click the Default button, PC-DMIS updates the JSON file. This defines the current values as the default values.