There is a way to ensure that you have the desired thumbnail displaying for your website on Facebook.
Please note: You will need Yola Silver or Yola Gold to use this option, and that Facebook requires a minimum size of 200x200 px for the image you use.
Please follow these steps:
1. Go to Site > Tracking.
2. In the Header Code box, paste in this code:
<meta property="og:image" content="http://yoursite.com/resources/yourthumbnailimage.jpg" />
3. Replace http://yoursite.com with the URL of your published site and yourthumbnailimage.jpg with the name of your image file.
4. Save and make sure you republish your site.
Now you can go to your Facebook wall and post your URL. The desired thumbnail image should come up.
If it still doesn't display, you will need to run your URL through the Facebook Debugger. To do this, please follow these steps:
1. Clear cache and cookies of your browser.Log into your Facebook account.
2. Click on this link (it must open in the same browser where you are logged into your Facebook account)
3. Enter your URL in the field provided and click on the Debug button.
Once done, try to add your URL to your Status box on Facebook. It should now show the desired thumbnail.