David Muir has done well for himself, very well, rising from the ranks of local TV News to the anchor of "World News Tonight," but with that seat change has come a sea change: a definite ploy to get younger viewers, and it appears to be working. 

PANELISTS

Callie Crossley is the host of WGBH News' Under the Radar.

Joshua Benton is the director of the Nieman Journalism Lab.

Roy Harris is an author and journalist.

Joanna Weissis a Boston Globe columnist.