How to change the vendor logo
The logo is the Gravatar associated to the vendor shop owner.
In order to edit the Gravatar you need to register to gravatar.com.
The Gravatar allows you to associate a profile image to an email address that will be recognized by all installations of WooCommerce, this is explained in detail in the Gravatar website.
In case you don't want to use Gravatar you can install this free plugin
which adds the option to disable the gravatar, under and use a custom image on a specific website, this plugin is compatible with our YITH WooCommerce Multi Vendor plugin.