audio track recording on second track while hearing playback

Hi guys

im so confused and would really appreciate some help!
I have a UR12 and im using cubase AI9.5. I have my head phone connected to the jack and my guitar in input 2 set to mono. My output is set to stereo. Because the steinberg becomes my sound card i hear all audio through the headphones. I lay my first guitar track track fine, i play my first track in my headphones while recording the second track. When i play back the second track with the first one muted i hear track 1 and 2 combined on track 2.
What the hell am i doing wrong? i can’t seem to listen to anything through the headphones while recording or it ends up on the track!