User CP
Edit Options (under Your Profile)
Scroll to very bottom
See this:
Message Editor Interface
When posting messages to the forums or other members, there are three interface types available to you. The simplest of these is a simple text box, while the last is a fully-fledged WYSIWYG editor, which allows you to format your text as you want it and see the results immediately.
Depending upon the capabilities of your web browser, you may not be able to use all of these options. If you experience problems when posting messages, try switching to a different interface type.
Message Editor Interface: Dropdown menu here; Select last choice: "Enhanced Interface..."
Save Changes
You will now see smilies to add to posts when you choose the "Post Reply" option, but not when you choose the "Post Quick Reply" option below.