In wpforo 1.1.1 i think there is a permissions bug.
When i search the Forum all Topics whith the keyword will be shown. Also these where User have no access.
In the preview i can read some text. When i click on it i can't see the Topic which are right. But ther should also be hidden in the Search
This bug is reported three time here and I've already mentioned that it's fixed and will be available with next 1.1.2 version in a few days.