I'm a new user, I've only been around for two days. I just found out that I could accept answers, because I was curious about those green tick things. At first, I did not know what they were. Now I know, but it was not immediately apparent to me.

I think that providing a little more information when questions are asked would go a long way towards solving the problems of questions with unaccepted answers.

I would add a little notice below the "Notify [email] daily of any new answers" message to say that I can come back and click the tick to accept an answer. For example,

The tick lets you choose / accept the answer that was most helpful.