Playback on one headphone & low audio input

[Kayleigh21972077nqau]

First off, I'm brand new to this, so I will give my best effort in explaining my two issues.

1) My playback from Audition is only coming out of my left earphone. Headphones are brand new, ATH-M30x. It was working at first out of both when I was recording some test tracks, and then when I started working, it switched to left only. Headphones work out of both sides when I play any other source, so I know it's something with my preferences in Audition. 

2) My input (I think that's how it's described) is suuuper quiet. Again, it wasn't at first when I was making test tracks, but today, it dropped to really, really low decibel readings, and I have no idea how. 

Thanks for the help.