Hi,

i have booked a trip from Copenhagen to Hamburg 2 months back itself. At that time, for that train no reservations were needed. still now just that journey exists in my trip without any highlights ( like ‘seat reservations needed’ highlight notification which I got for some other trips )

now I thought to change time of my journey and now it says seat reservation needed. So, I did not do any change. 
 

my question is if I continue with my original journey booked 2 months back, for which I have ticket (QR code), will it be sufficient or do I need to reserve seats there also? 
I am confused because QR CODE DOES NOT HAVE ANY SEAT NUMBER ,it just says second class. Kindly help me.

Note; I have monthly EU global interrail pass