Nikon D7100?

The problem lies with the live view.
"Live View" on a DSLR is not the same as the screen on a P&S.
You can hold a P&S at arm's length in the typical snapshooter's position (and that is such a bad technique), but thankfully you can't do that for very long with a heavy DSLR & lens combo.
Live view has its uses occasionally , for instance for macro shots, but it isn't instant like the display on a P&S, it sort of lags, and just doesn't feel right.
Live View is not meant to replace the view finder, a serious photographer uses the view finder because it is vastly superior, full stop.
I was excited about my first DSLR with live view, but very quickly gave up on it again - the view finder is so much better.

If you are serious in learning photography, you don't use LiveView.

If you simply want to use the dSLR like a point-and-shoot, you shouldn't be bothered with aperture and exposure would you?