Jack Dorsey’s future as chief executive of Twitter will ride on the answer to a single question: Can he persuade the world’s Facebook-addled masses to take a fresh look at the bewildering 140-character messaging service that he helped found in 2006, a service that millions have already tried and abandoned? He is apparently keen to act fast. A day after  Twitter’s board announced the appointment of Mr. Dorsey as permanent chief executive , the company unveiled a long-awaited new feature aimed squarely at attracting people who now find  Twitter  too confusing to use. The feature, called Moments, tries to transform Twitter’s chaotic timeline into a series of narratives that are easily navigated by people who aren’t familiar with the service’s strange rituals. When you open Twitter on your phone or on the web, you will now see a new Moments section alongside the standard timeline. Tap it and you’ll be taken to a half-dozen or so headlines pointing to ...