I have the subscribed view on at home, and my sub view stays on all the time. I've not had it revert automatically, even after unplugging from the power source.
To clarify, are you using the below method to filter subscribed channels?
Mine stay as Subscribed only. They shouldn't revert back to All Channels on its own. You can also customize your guide and remove any channels from it that you don't want to see. I've done that also.