So's not to sound to stupid, this is the first time we are in the rv in the winter. Having a problem with windows, closets and compartments getting wet and then of course mold sets in. Is this normal ...
Open it up when using the heat and it's cold out. The walls are cold and are condensing water vapor, vapor you are giving off and from the heat itself. I've camped many times in the winter and I always leave a window slightly open and roof vents open as well.
I know it sounds counterproductive but your house breaths ( exchanges air) your RV don't.