i'a a new user of magento, when i add a new product use Simple modle, the products need size attribute,i add it through custom Options,but i have some many products need to add, is there some more convenient way to add size attribute ?? thanks for your help !!
This extension might be of great help https://amasty.com/mass-product-actions.html
It will let you to copy attributes and custom options and add them to other products. All the cations can be permormed in bulk, so you'll save much time.