So finally here is the solution self tested and tried. Im copying ehsan's text with the added step.
Keep the CNG button pressed and start the engine then let go of the button
- One light will blink, press the button for 5 seconds till the next light turns on.
- For CNG RPM setting, this will be the fourth and last light
- When the RPM is at desired position, press the button once. Green light will was blinking will turn off, and the setting is yet to be saved.
- Keep button pressed for another 5 seconds and you'll see all lights blinking. Now the settings are saved. Turn off the switch and voilaaa....
you have done it...
Regards
Adeel