More teens are entering adulthood with an established credit history after spending years as authorized users on their parents\u2019 accounts. J.R. Whalen is joined by WSJ personal-finance reporter Oyin Adedoyin, who explains the pros and cons.\n\n\n\nSign up for the WSJ's free Markets A.M. newsletter.\n\nLearn more about your ad choices. Visit megaphone.fm/adchoices