Changing quantities ordered in checkout

[nadsab]

Hi,

Is there a switch in Admin where I can turn on the ability for customers to change or add quantities of an item they order?

Right now the only thing they can do to buy multiple quantities of teh same item, is add an item to the cart by clicking on it in the product list over and over again, either that or delete it. Highlighting and then changing the number of items does not work.

Thanks.