No permission to this forum , returns from mobile to classic

Hello.
I just found a problem,
I test my forum by viewing it from phone.
This is what happened.
The button New topic is appeared even if you are a visitor.
Ive created a forum , in which only Admin can open a topic.
I logged in as a simple user , and I touched the button "new topic".
It asked me to log in again (even if I checked the dropdown that I was already logged in and the button "logout" was appeared there).So I logged in again , and after it redirected me to the classic version and it left the mobile version.
Can we fix that?
Please?

Thanks.