I have never stored them I always just cut the plants back, left them and their dirt outside and in the spring they came back. This worked for 7 years in my flower boxes.
If they were my seeds I'd freeze them till spring but if that is incorrect I am sure someone will correct me.

Well, I can't say impatiens ever overwintered for me. Not even indoors though a relative does cuttings successfully.

Anyway, I like to store my seeds in either a small coin envelope or a small hobby ziploc. I don't think you need to keep impatiens seeds in the fridge. I would keep them at an even living temp, dry, out of the sun.

Unless you mean jewelweed or the balsam types - those reseed.