[nosdevoirs]

I want my forum accepts a single user response (in one subject). And I want him to create the subject should not answer

[Robin W]

I suspect that English is not your first language, but the above makes little sense.

Please type a longer requirement into google, and use an internet translator to post a fuller set of requirements.

[nosdevoirs]

How do I do?
Comment je fais ? Je suis français

[Robin W]

utiliser un service de traduction sur Internet pour traduire votre question du français vers l’ anglais, puis poster les anglais ici

[nosdevoirs]

I want that my forum must accept one only answer per user

[delarno]

Although you have limited English to express what you really want, i don’t think the problem is mostly language but the request. How come and why you would set a forum to “accept one only answer per user”? What if a question requires multiple answers from the same user due to lack of clarification?
I don’t know if other programmers share my view, but honestly, it does not make sense to me.