That is so annoying! I had no idea there was a setting to get it to scroll inactive windows like that. That is the problem with Windows. There are so many ridiculous settings that are nonsensical I can't imagine who would find it useful to enable the mouse to scroll everything like that. All you need to do is hold the scroll button on the mouse down when you want to scroll.

Microsoft is bloatware. Some little nerd decided that functionality was needed when in reality its absurd. I don't know how you wife dealt with it before you turned it off.