If you need support from Yola please contact us via firstname.lastname@example.org or make use of our live chat service! We are working on a new approach to community-based support and during this transition period we are not adding any new threads to this forum. Many thanks to everyone who has participated over the years and we look forward to unveiling a new peer-to-peer support system soon!
I presume that your avatar for our Support Forum is your logo because you also added it to your Online Store Control Panel. I can see that you've also added it as a banner image on the home page of your Yola website. However, if you post a link on Facebook, it will not pick up any banner images, but only (some of the) images in the content area of a page. You would need to add your logo to the content area of your home page to have Facebook display it, i.e. add the logo using a Picture Widget.
Another option is to post a picture on Facebook, use your logo as the picture, and then add your text and links to the text area.