Why is the Wix information and thumbnail, shared on Facebook, not up to date?
Please make sure that you have added your personal Facebook Account username (and not your Business page username) under the Social Settings section of your Wix account.
To add a Facebook username: From the left side of your Editor, click Settings > click Social Settings > under Facebook Username, type your username > click Done.
Facebook may take some time to process your site information. If you post to your Wall directly and the information is not up to date, use Facebook's Debugger here. Simply type your site's URL in the Input URL field and click Fetch new scrape information. The Facebook Debugger will process your site so that the title, description and thumbnail pictures appear up-to-date when you post your site to your Wall or Page.
Note: The Facebook API only works with personal Facebook account usernames. Any features related to your Facebook Page (sharing your website on Facebook, managing comments, likes and etc), require administrator identification on Facebook. The owner of the page will be set as the administrator of all the pages he has, which is why the personal Facebook username is required.
This information is not displayed to users who visit your site, it is only for the purpose of Facebook admin related functions.
Note: The user name is not your name on Facebook, it appears in the location bar of your browser after "https://www.facebook.com/" when you view your personal Timeline page.