Forehead is too far back, which does not show off your jawbone.
Bring your forehead forward and presto! I would say that his chin is a little too far back.
He brings his chin a little forward so it's on the same field as his forehead and bingo. Also turning your body to one side can help show off your jawbone as well.
His head is too relaxed and back.
Bring your forehead forward and...BAM it's gone.
You also don't want to bring your chin to far up, remember we don't want to see up your noise.
Conversely we usually don't want to bring our foreheads to far down because we have to look up with our eyes which does not make for the best shot.
Simply put your forehead forward and your golden!
I hope you found that useful!