Well, I was in the WIFI section of my settings, and I have seen "Back to ...(whatever app got me there)" in the past but having just chosen to look at WIFI settings, it did not dawn on me it would show me the previous app when it wasn't the one that took me there.
I switch between apps frequently and never see the previous app in the top bar unless the previous app took me there.
Thanks for the info, though. New to iOS 10, so not seeing "Back to..." I was not familiar.