Bill Whitaker goes behind the scenes of cyber assaults on U.S. voting systems. Oprah Winfrey reports on a monument dedicated to the thousands of African Americans who have been lynched. Dr. Jon LaPook sits down with a couple, of which the wife has Alzheimer's disease. "60 Minutes" has interviewed them yearly for the past decade to illustrate the disease's impact. Those stories on tonight's "60 Minutes." Learn more about your ad choices. Visit megaphone.fm/adchoices