If you use rocketthemes (rt_sporticus_news in my case) you can go to theme's index.php and there are two lines to config your menu:
//Menu stuff:
$menu_type = "supersucker"; // module | suckerfish | supersucker | splitmenu
$menu_name = "mainmenu"; // mainmenu by default, can be any Joomla menu name
You can replace "mainmenu" with "sections". It will work fine!
However, If you want to show categories as sub-menus under sections. The above way doesn't help. I suppose this is a point news portal needs to improve.