Massive layout problems

Hello dear supportteam
this question is related to this topic:

Since hours i try to config the view of my categories but what ever i do ….nothing ever happens

1: Where / how can i define the number of columns i want my posts to be in in a category?
2: Why are there so many options regarding the blogmeta – but nothing changes of you change the settings?

I found this in another thread:

add_filter('avf_which_archive_output','avf_change_which_archive', 10, 2);
function avf_change_which_archive($output)
{
	if(is_category())
	{
		$output = single_cat_title('',false);
	}

	return $output;
}

What are these numbers supposed to do?
add_filter(‘avf_which_archive_output’,’avf_change_which_archive’, 10, 2);

Shouldnt they define post-count (10) and number of columns (2)
I guess so…
But if i use this code in my functions.php …nothing changes…it stays 3-column

Please dont let me go crazy over that ;-)
Save me!

Kind regards
Ricarda