Well, I just tried to put a thumbnail for a "New product", was simply in the product edit, store settings, store display - image 😛
By the way, do you know if there is a way to add custom product stock ? I mean, for virtual product to sell keys unique key per user to use my program so once the customer completed the purchase the unique key will be delivered to his mail/order manager? Any application/plugins ? I don't see the option to add key one by one and to sell them ^^