I've set my configurable product on "in stock" but it still shows out of stock! :S I don't understand why.. I don't have this issue with "simple producht"
You should have a grasp of what Configurable product is and when you need to use it and when not. and what it is doing:
suppose you have a Tshirt,the configurable product is Tshirt with attribute "color"
- tshirt 1 has yellow and red so you have two different simple products here
- tshirt 2 has green blue you have two different simple products here
- tshirt 3 has black you have one simple product here
you need a parent product of Tshirt which is a configurable product and simple products of tshirt1, tshirt2,tshirt3
see this diagram:
if you are confused you can do it simpler like this:
Here the configurable product is a Tshirt and Tshirt has two different colors and so two different simple products
so you have to know that each one of associated products should have QTY now look at this one:
as you are seeing when you created your configurable products you should assign your simple products to it in associated products section and then you should have QTY in each one of simple products more than zero also remember that the simple products visiblity should be not visible indivudually bcause you don't want to show each one , one by one