Its a bug...
https://coderanch.com/t/574339
Setting permissions for Forums and Categories
By default, JForum will create the Forums with some permissions set to "not allowed" for the users / groups. This is incorrect jforum's behaviour and will be fixed in the next release. So, in order to allow users to insert / reply / edit posts,
you should first give the right permissions for the group - by default, "General" "Administrators" and "Moderators".
The steps are easy, but must be done to every new Category and / or Forum: After creating the category / forum, go to the "Groups" administration, using the link in the left menu and then click on the "Permissions" link. A page with the current existing roles will show up. Now, check if everthing is according to your needs, and the click "Save". You must click save even if you don't change anything, so the roles can be written to the database.
That's all you should know for now to start using JForum. Don't forget to read the other sections, and don't be shy to ask something if you have doubts or problems.
Anonymous wrote: :?: After installing the JForum-RC5 software, I get no 'NewTopic' button - am I just being stupid? Or is there a setting I have to turn on to allow pppl to post? Thanks!
[originally posted on jforum.net by Anonymous]