My wife got a D610 as an early chrissie present

Anyway as I am without camera I noticed when helping her set it up the way she wants (after all its hers) that there was a U1 & U2 settings.

I RTFM but still didnt understand how a camera could have one lot of settings and then if I was to use the camera, put my own settings in!
I shoot Manual, Di shoots P mde. When I, like most use manual I am forever changing setting while looking in the viewfinder.

My question is: DO I go to U2 and then setup the camera? Seems confusing because I cant setup settings as they always change in manual due to the surroundings changing every minute. I dont want to upset Diana's settings but I need to use manual..

*Cant afford to get another body so no choice*

Thanks in advance