I have been trying to change the thumbnail that shows up when I share my site on facebook. Only thing I get is the image I've uploaded in my page settings. That image happens to also be the main banner for the page. I want that image to stay the same but want a different one when I'm sharing my site on facebook. I've tried inserting code in the header, the facebook debugger recognizes both images, but I can only choose the main banner image thumbnail and not the different one I want for it.
Please let me know if there is a fix for this.