I use Windows 10 (because I was foolish enough to upgrade from 7, but never mind). They have, for over a year, not accepted my refusal to let Cortana™ learn my voice and answer my questions. With each upgrade or service pack, I get a new set of amazing questions Cortana™ could answer for me.
Today's suggested question: "Cortana, how many meters in a kilometer?" Seriously. As bad was "Cortana, what is the square root of 256?" Clearly, MS thinks I'm a moron.