Q: Since Sierra, trackpad on MacBook Pro keeps turning itself on...

I normally use a Magic Mouse and have the preferences set to ignore the trackpad while using the mouse (in System Preferences/Accessibility/Mouse&Trackpad). Ever since I downloaded Sierra, whenever I boot up the computer, the trackpad starts working, along with the mouse, even though the check box is clicked that supposedly turns the trackpad off. I uncheck it, then check it again, and this disables the trackpad. But the next morning when I reboot the computer, the trackpad activates itself again, which I usually don't discover until I realize I've been typing in the wrong paragraph because I accidentally touched the trackpad and it relocated my cursor. Anyone else having this problem and/or know of a fix? Thanks.