How to make my answer accepted by default.

Hi,

My discussion forum will allow member only to add questions and not replies. Only me as admin will be able to reply. So there is not multiple answers to choose only my own.

How can I make by default the answer show with the green background as being accepted?

If this is not possible and I have to make it manualy by cliking on the button, how do I make the button to accept an answer not show to the member that post the question but only to me as administrator?

Thanks