Your question is vague and confusing. Are you saying that your NU account logged you out automatically?
when i log out the main page ( not the forum ) refresh and my account is connected is return to the beginning but when i log out in the forum i can log out in the main page ( not forum )
So you're saying that when you log out of your NU account and refresh the page, you're logged back in? Try logging out of NUF before logging out of NU. NU and NUF are linked in an odd way that sometimes requires you to login to NUF before you can login to NU and vice versa.
If you want to totally log out. Log out from NUF first then log out from NU main page. True logging out from NUF not usually mean you log out from NU main page.