Well, this has already been explained somewhere else, but here it goes anyway.
When a question is posted, it is marked as "Not Answered". After the first reply, and regardless of its content, it is marked as "Possibly Answered". From then on, every time the original poster is to add a new message to the thread, s/he is offered the options to give the question as answered or not answered. As the default is not answered, a majority of questions tend to remain as "Not Answered" for ever. However, if the OP marks it as answered, s/he can no longer change this choice.
There should be a way of marking it read or not read, instead of answered or not answered, so the user could go to the last read/first unread post .... But Jive is made for asking questions and getting quick answers, not about conversations.
I know, I know ... As the sheet of paper said to the ream, "You're preaching to the quire!"