Prevent customer from adding more stock than is available?

Hi - I'm sure there's a simple answer to this somewhere but I can't seem to find it. I'm using Zen Cart for my fused glass jewelry store - which means I'm selling products that are one-of-a-kind. The stock will never be higher than 1 for nearly all of my products.

I've noticed that when a customer accidentally tries to add a product to their cart when they already have it in there, Zen Cart gives them an error message telling them to reduce the quantity to conform with the stock level. "Please change the quantity of products marked with (***). "

The problem is, I disabled the quantity field because my customers don't need it, so the only way to fix the stock issue is for them to delete the product from their cart and then re-add it.

Is there a way to change this so that the product isn't added to the cart at all when the stock level is inadequate?

Thanks!
-Lis

You might check your Configuration ... Stock settings ...

You can make the products that are out of stock sold out ...

Or prevent checkout when not enough is available unless they lower the amount that they want ...