To turn on the USB debugging, you can use the following steps.
a) Go to “Settings” -> “System”-> “About phone” -> “Build number”.
b) Touch the Build number no less than 7 times.
c) Touch “OK” on the pop up window to allow development setting, you will see a warning that mentions that developer mode is already turned on.
d) Go back to “System” again, you will now find the “Developer options”.
e) Activate “Developer options”.
f) Activate “USB debugging”, touch “OK” on the pop up window to allow USB debugging.