Need help getting bold/italic/underline to display in topics/replies

Technical Details

Forum version : phpBB2
Position : Administrator
Concerned browser(s) : Mozilla Firefox, Google Chrome, Internet Explorer
Screenshot of problem : https://i.servimg.com/u/f38/19/12/40/14/screen11.png
Who the problem concerns : All members
When the problem appeared : Since forum creation
Forum link : ( link is hidden, you must reply to see )

Description of problem

Hi there. We seriously need some help with this new forum.

When you post a new topic/reply, as any user, the bold/italics show up properly when first posted.
However, when you edit anywhere on that existing post, the formatting will show up as html tags [b] and I can't get it to display properly again.

Please help! This is a really annoying problem, and it probably has a simple solution that we can't find!

Here's the culprit screenshot should you need it

click very last button right above box your type in it looks like sheet of paper theirs two modes one lets you see the code the other lets you see the effects