Hi,
I was wondering if there is a help file or a documentation available that the users of a forum can refer to. For the admins etc there is the codex, but is there for example a written text or step-by-step-guide on how to use the image uploader?
I’ve got quite a few users that even complain to not have found a button when its color has changed 
basically no although it is something I have toyed with doing and would like to do – and that is just a matter of finding the time.
If you are using the tinyMCE editor, there is a help button that will supply some very basic guidance but it IS basic. This was introduced in V5.2 to see if we got any feedback on it and if wanted it is an area we can add more help to. But it seems that your users di not find that so that exercise is probably pretty worthless 
Someone did put together some tutorials here. http://www.byobwebsite.com/answers/problem-with-post-edit-buttonow-to-use-the-forum-part-1-configure-your-forum-profile/
I can’t vouch for them, I have not actually watched he videos, but you may want to take a look. If you think they may be useful you can contact them in regards to using them for your site.