How do I store untempered chocolate?

They are not that much meltable. Also, there is some chance they will become actually more pleasant, since the unstable crystals tend to turn into the next higher type over time.

So, I would just keep them at room temperature and not worry much. If milk chocolate (or worse, bad quality milk chocolate) doesn't spontaneously bloom in your place, your untempered chocolate shouldn't melt either. And it does melt slightly and then re-sets, it won't be that much worse for eating than plain untempered chocolate, maybe it will just have some added fat bloom. I have eaten many advent calendars in that state.

The fridge is also best avoided for great quality chocolates into which you invested lots of money or effort, but if they are already in the "I'll eat it so I don't have to throw it away" state, it doesn't matter that much. You can therefore use the fridge, if you prefer it over the room storage. They won't actively soak up any kind of moisture while they are cooled. What will likely happen is that you will see some condensation when you get them out for consumption and they warm up again. They are perfectly edible in that state too.

Bottom line, people tend to pay great care to perfectly-tasting chocolate, but once it is less than perfect, it is unlikely that you can make it significantly worse by storing it in the wrong place.