Hello. re: Nexus, I am trying to find out if there is a setting that brings apps to focus when they are opened. Some of mine do, but others do not. Thanks very much.

Standard behaviour when launching apps - whether through Nexus or not - is always that they take focus, with very few exceptions. If some standard apps don't get focus when launched, that would suggest there's something very odd going on in your Windows system, as far as I'm aware.