It can be changed within index.php using the theme editor in the dashboard. You just have to search for the following codes;
wp_list_categories('show_count=0&title_li=&depth=1');
and add the “hide_empty” parameter to the list. Just put after depth=1 the &hide_empty=0
To make it look like this;
wp_list_categories('show_count=0&title_li=&depth=1&hide_empty=0');
