BuddyPress.org

Hi, I have just started using Buddypress and have a few questions:
1) On the Groups page the title is “Group Directory”, how do I change the text to something else?
2) Within a Group there is a “FORUM” tab, how do I change the text to something else?
3) Within the Group page there is a “New Topic” button, how do I change the text to something else?

Any help greatly appreciated