Cannot set "levels to expand" to 0 and "Apply" button seems to be disabled in a RRC view

This is happening in RRC 4.0.6, using a FF supported version.
It seems I cannot set the "levels to expand" = 0  or to any other level, whether a link is selected to show in a tree view or not. The "levels to expand" is always automatically set back to 1.
Furthermore, the "Apply" button seems to be disabled. Do you know why?


Is there any explanation for this behavior?
FYI - I have Project Admin permissions and also Author,  Administrator and Project Baseline Administrator permissions.

Thanks!
Vicky