How can I turn on USB debugging?

To turn on the USB debugging, you can use the following steps.

1) Go to “Settings” -> “System”-> “About phone” -> “Build number”.
2) Touch the Build number no less than 7 times.
3) You will see a warning that mentions that developer mode is already turned on.
4) Go back to “System” again, you will now find the “Developer options”.
5) Activate “Developer options”.
6) Activate “USB debugging”.