Help understanding the power system on our new Interstate

We are new to this and have read the information provided, but are still trying to figure out the power system. Hooking up to power is easy and works great. When we are on the road, we want batteries to run the fridge and lights, and that seems fine too. When we return home and want to shut it all down, so we don't drain the coach batteries, I was told to hit the kill switch by the door. 24 hours later the fridge was still running, so we used the red switch under the sofa.



Any clarification,in terms a newbie can understand, would be great! We love our rig and look forward to many new adventures!