Woocommerce / Can't change the product image size (stuck with 450px x 450px)

Hi everyone,
I’m facing a strange problem with woocommerce and enfold.

I would like to show my product image on the single product page with a resolution of 600px x 600px.
So on the Woocommerce configuration screen, I set for the product image size 600px x 600px : http://adelineaffre.com/images/bug.png

But in the front office, the product image is blur and in the code I have an image size set to 450px x 450px :
http://adelineaffre.com/images/bug2.png

You can see an exemple here : http://adelineaffre.com/website/bijou/pendentif-seul-a-personnaliser-argent-massif/

I don’t know what to do…
Thank you very much for your help !

Regards,
Thibault