Look here: bham.clivio.pl/forum/spotkania

The KUP REKLAMĘ module should be more to the right (it is on position-7 - demo.smartaddons.com/templates/joomla3/sj-news/images/position.jpg). And forum should take more space.

I've overriden the layout for menu positions (option main-right), but it doesn't work when I open a category or a topic.

I solved the problem, I mean I made the forum full width and I don't need the answer for this question, more important is for me other topic where I'm asking about polish characters in footer menu.