Yamaha psrs670 recording function

[leo35]

Hi everyone, I recently got a Yamaha psrs670 and
Love the voices and styles; my only problem is that
I can only record the first four tracks...minus the
Accompaniment part (which I also can't play the melody at the same time, and add other parts, why is that?,)  I thought you could record up to 16 tracks? Thanks, happy labor day.