Found the problem for the “Go!” issue. I did not code it correctly. Please use the Email Support form (off the Support home page) and I will send you the corrected .pot file as well as the searchform.php file (both will be in the next update of Preferential).
The Media settings is actually not for the featured image but only for images you insert yourself into a post or page. The featured image has to be coded directly in the blog files. I have decided to code this in, so I will do this today.