DDJSB3 - RCA Output Audio Phased? / Phones output malfunction

Hello, 

I am stepping outside of my comfort zone and am a first time DJ here! 

2 separate (maybe connected) issues that I can't seem to find the answer to. 

1) when I plug in my rca to 1/4" cable to either a mixer or directly into monitors, the audio sounds almost like its got a phaser effect to it. It has the mids distorted and sounds like the audio is distant (faintly). I checked all my effects and all of them are off. This distortion in audio is only heard when I play tracks on Serato. When I play from a streaming music service with the same connections, the audio comes out fine. Any thoughts? 

2) Whenever I use the RCA outputs to play directly into monitors or mixer, the audio coming out of the phones malfunctions. Both channels are played regardless if the proper channel selector is pressed (1 or 2) or whether the MASTER button is pressed as well. When I play audio through my computers sound card, the phones output works normally and I am able to control the phones volume and which channel is selected when doing so. Any thoughts? 

THANK YOU!