How to change USB Settings in LG G3 cat-6 to enable USB Debugging option.

Hi, i am an android developer, and i am trying to run/test my app on my android device i-e LG G3 cat-6, which is loaded with custom ROM, but when i connect it to my PC and run the command on terminal/ADB "adb devices", it doesn't show any device, as my phone is not recognized by my the PC or ADB...

How to change USB Settings in LG G3 cat-6 to enable USB Debugging option.

How to change USB Settings in LG G3 cat-6 to enable USB Debugging option.