Graham Nash sang about a changing world for more than 50 years as a member of the supergroup Crosby, Stills and Nash, sometimes joined by Neil Young. After the final breakup of the group, and Crosby’s death, Nash is touring to promote his solo album, called “Now.” He plays the Pageant on Thursday. St. Louis Public Radio’s Jeremy Goodwin asked Nash his legacy and how he likes life as a solo artist.