3.7.4. Websites
fmProducts
If you’re managing multiple websites, you may select the website(s) to which the product(s) that you have selected are associated, by selecting the checkbox next to the website(s) in which you want the product to be available.
Each available website is displayed, with all of its associated Stores and Store Views, to facilitate selection of the correct Website or Store/Store View.
The similar option which helps to assign products to the relevant website is located in the top toolbar as well: