Traction theme – adding byline

hi there – we’ve just purchased the traction theme but noticed all the bylines have disappeared. i’ve been looking around on this forum but can’t find the answer to how we can reinstate all the bylines.

or have we permanently lost all the bylines and all we can do now is add bylines from now on? if so, how do i do that please? i’ve read something about the loop but can’t seem to figure it out… thanks.