what is main template used by forums?

Would greatly appreciate help with the following:

Am fairly new to wordpress, buddypress and bbpress but not new to programming. Am looking at modifying how bbpress behaves and am trying to figure out where the code is to do that.

When I go to mysite/forums which is the main template which has the code which runs for that?

My BuddyPress settings have the Forums WordPress Page associated with a page called Forums. The Forums page in turn is set to Default template. Nothing I type on that page appears anywhere (that I can see), so I assume the page is just a placeholder.

When I look in among the templates there are more than a few with the word 'forum' in them so not sure where to start.

Pointers on what to do or where to learn what to do would my great.

Thanks in advance,

William