It is not really a problem other than design and use. : Newer radios, TV's, etc have basically TWO power lines. One called the "keep alive" and one the normal on/off. In normal use, you turn the radio off with the on/off power button. The radio goes to sleep. The keep alive voltage is still there and it maintains, the clock, channel presets, volume level etc. forever. In an RV, when we shut them down they usually shut off the "keep alive 12V" line also. So after a few hours (or days) the radio completely loses it's "mind". So when you turn on the main power to the RV, the radio wakes up with a completely new "mind". That means it will come up to whatever the manufacture set as the default (or maybe just a random condition). They could keep 12V on the "keep alive" line but there is a slight current draw and after a few weeks of storage your battery might die.
So nothing is wrong. It is just the way it works.
BTW, if you turn off all the power to your house at the mains for a few days and then turn it on, you will also experience a few anomalies. Same with your car at the car battery..