A:Answer It should be in settings under display, however, if is like my 3D TV should be able to detect a 4k signal and change automatically.
Ps. Unless you have the full 4k setup (DVD, DVD player , HDMI and TV or PS4/ XBOX/ cable service and TV) changing the resolution doesn't affect the input signal.
In simple words you can't view a 720p DVD and expect 4k resolution, it doesn't work like that.