In my LG Android 5.0 phone it's setting for the USB, as described in http://www.verizonwireless.com/support/knowledge-base-161574/ and in the user manual (that I downloaded as a pdf).

Maybe it was different in yours. What does the user manual say about it?
Maybe it's still the same after your rooted. Maybe it's different. Did you ask the author of the root?

Before editing the registry on my PC I would have tried another PC.

Kees