Sorry, Fernando.. misunderstood your questions.
Groups in Online Users block: In order to see groups in this block you'll need to activate site groups (Administration » MoodleFN » Site Groups), create groups and add users (via the FN Goups block).
Privileges option not showing up in Teacher Tools block? I'll have to look into this and get back to you. Might be a role thing.
Image of the block Announcements not changing to yellow? Probably a bug. I'll try to look into this soon.
Thanks,
Fernando