If you scroll down that page to 'Adult content options', you need to set 'Viewing Adult Content' to 'Do not collapse' and then set 'Safe Search Filtering' to your preferred level, which is most probably 'Do not filter my results'.
NB: This only works if you are an adult in the eyes of LJ - ie, if you gave an appropriate DoB when you set up your account, or (if you set up your account before they added that requirement) if you have an appropriate DoB listed on your profile. (You can set that to be hidden from view.)
The explanation for all this can be found here in lj_biz. I advise you to read the comments carefully as some rather important/obvious questions have been answered there but not edited into the main post because, hey, that would be too easy, right?
Look out for replies by marta (also known as pheret1) - she's joined the LJ Team to help out with customer service and community issues, so her word is, or should be 'gospel'.
I see a sudden spate of new 18+ LJs being created by all those tweenies who didn't lie about their age when they created their first LJ and now suddenly find themselves cut off from all their favourite comms.