Ya, don't let your members post HTML. It's just asking for all kinds of trouble. I don't even like to let my co-admins use html; one wrong tag and the whole forum gets messed up.
in some of my forum i have html allowed that's why they are able to post html if change all my forums to no html will my threads will be effected as i have been posting my threads in html
yes i tired that also doesn't work i just want my post to be html to my users
It is possible to allow HTML in selected forums through the Forum Manager (first pair of radio buttons in the last section) You can make these forum hidden or unpostable to unregistered/untrusted members ...