Here are the steps to setup touch on the second screen:
1. Ensure the external display is in Extended Mode (To select Extended Mode, press the Windows Key + P together at the same time)
2. In Desktop Mode, click on the Start Menu (Windows key), choose Settings and then Control Panel
3. Select View by Large Icons, choose Tablet PC Settings and select Setup
4. Both screens will have a white background and the primary display will show the text Touch this screen to identify it as the touchscreen and If this is not the Tablet PC screen, press Enter to move to the next screen. To close the tool, press the Esc. Key
5. Touch the same screen once
6. You will see a white screen with the following instruction Press Enter to proceed to the next step to complete your configuration
7. Press Enter to synchronize the first touch with the first display
8. Repeat Steps 4 to 7 to synchronize the second display
9. The dual touchscreen displays are now setup for use