I want to add configurable product to grouped product but when I search magento show me only simple product. How to change this?
Magento does not come with this option by default, but someone else has created an extension:
Grouped Options by BRIM does exactly what you are looking for. I have bought and tried it out but we ended up going in a different direction.
Unfortunately, you can't do that.
Magento Grouped Products are just a collection of Simple products. You are not able to have products with custom options (Configurable Products) inside a Grouped Product.
More details here: http://docs.magento.com/m1/ce/user_guide/catalog/product-grouped.html