I have new wooden cookie mold that must be oiled with each cookie. I had to throw it away because it smelled rancid after storing. I could not get rid of the smell. How should I store it?

When using wood in a kitchen it is important to keep it clean, sealed with oil, and away from moisture. After using it, clean it well with a very mild soap. Then let it dry, very well. Leaving it in the sun will help to disinfect it well, if not, leave it overnight or even dry it in the oven at a very low temp. The key is making sure there is no moisture because if there is, bacteria will live there. Next make sure to seal it so moisture doesn't seal in, using cooking oil does a fine job, there is also wood sealing oil. Either way, oil it twice a week, unless you use it often, then oil it every week. Just like any wood, you are treating it to keep it healthy.