When a user clicks on any thumbnail picture in the search result listings it starts a slide show of all the thumbnails on the current page. When you upload your thumbnail picture we store two versions, a small version scaled to fit the 160 x 120 pixel (80 x 60 pixel for Basic and Plus) and the original version you upload. If you want to change your thumbnail picture just log in to your account and upload a new one which will replace what is currently there.
We recommend you scale the picture you plan to upload to 72 dpi and no more than about 450 pixels wide. You also need to keep the total size of the file below 200k and in jpeg format.