Product BUY NOW button does NOTHING, but ...?

[kevinmc3]

And, since you've disabled their ability to edit the quantity they've put in their cart, you give them no way to fix the problem other than to completely remove the item from their cart and then go find it again somewhere in your store so they can add it back again.

Re: "And, since you've disabled their ability to edit the quantity they've put in their cart, ", I can change this in Admin/Config?

[DrByte]

Re: "And, since you've disabled their ability to edit the quantity they've put in their cart, ", I can change this in Admin/Config?

Yes. You've changed settings to make that happen, because the default in a new install of Zen Cart is to not prevent editing of cart quantities and also to not prevent checkout when the qty in cart is greater than qty on hand.
Admin->Catalog->Categories/Products->edit the product->"Product Quantity Box Shows" ---- The default is YES, but you're using NO.