Not changing language

Hi I have installed WooCommerce on my site. My site language is set up in Spanish, but for some reason WooCommerce back end and front end doesn’t change to the set language.
The add to cart button doesn’t change to the set language the same happen on the preset pages of WooCommerce like register, check out and cart.also my WooCommerce dashboard and products are all in English.
How I can fix this?
Thank you