the popups and options assume an understanding of SEO and what you are doing on your site… if there was a simple, one answer fits all situation, we would have just done it a singular way… but ask four folks about best way to do something for SEO and you get about four different answers… so we have tried to cater to the folks who want to do it differently…
so if asking me, I would:
in title section, check all options but the exclude forum name one…
enter a custom meta description that describes what your forum is all about…
enter some custom keywords that describes your forum…
in meta tags setup, select the last option for both description and keywords…
in next version, you will also be able to add a custom description for each forum…