Audiences shared by your partnering Retailer are a good way to start building your Ad.
However, if you need to make changes to the saved audiences, you need to build a new Audience and save it as a template. You can hover over A Saved Audience to review its targeting options. You can use this as a reference in creating your own version of the audience.
Once an audience template is saved, you can reuse the template for your future Ad campaigns.
To know more about Templated Audiences and how to create one, you can check this guide.