new owner exchange ownership

I doubt anyone here would understand what you are asking. Please read Writing an effective Apple Support Communities question.

What to do before selling or giving away your Mac - Apple Support

What to do before selling or giving away your iPhone, iPad, or iPod touch - Apple Support

Turn off Find My iPhone Activation Lock - Apple Support < AFTER you receive a device and the above has NOT been done

iCloud: Remove your device from Find My iPhone < AFTER you receive a device and the above has NOT been done

Another tip is the one I wrote*:

http://www.macmaps.com/selling.html

* Links to my pages may give me compensation.