DDJ - 400 - Problem with DJing on Headphones

Hi all! 

I'm very hopeful you will help me with my enquiry. 

I have Covid-19 and I am stuck at home for 14 days and I really want to use this time to learn how to use my DDJ-400. 

My flatmates do not allow me to DJ on speakers, so I need to DJ on Headphones. 

Unfortunately, when the volume is only in the Headphones, I cannot control the volume of the loaded tracks while listening on Headphones. 

They just blast full on and I cannot practice transitioning between the songs. 

Please help! It's literally a matter of life and death. 

Thank you :)