In the settings for Configure ... Shipping/Packaging ... there is a setting for:
Display Order Comments on Admin Invoice
Do you want to display the Order Comments on the Admin Invoice?
0= OFF
1= First Comment by Customer only
2= All Comments for the Order
and one for;
Display Order Comments on Admin Packing Slip
Do you want to display the Order Comments on the Admin Packing Slip?
0= OFF
1= First Comment by Customer only
2= All Comments for the Order
Change the setting to 2 so that you see all Comments and not just the first one ...