set max terms

Sorry, there’s no way to do that in this plugin or in the WordPress core function it uses, wp_list_categories(). The closest thing you can do is to exclude specific terms by ID (which this plugin provides a field for) or to use the function yourself (without the plugin) and use the include parameter to only include a specific list of terms. (see http://codex.ww.wp.xz.cn/Template_Tags/wp_list_categories )