To help your older children solve problems, ask, don't tell.
The older your children get, the more they need to figure out what to do for themselves. If you are concerned about something your teen is doing, explain your concerns. "I know you love to play video games, but I worry that you don't finish your homework until midnight." Then, ask for your teen's idea. "How can you change your schedule so you can finish your homework and get to bed by 10:30?"