Krell S-1000 Menu problems...

I recently bought a Krell S-1000, And having problems with the menu. I get all the settings set, then when I try to go back into the menu to tweak them, it says "not allowed". It's very frustrating, what am I doing wrong, and how do I unlock the menu? UUUGH!!! Also, I have an oppo 93, and I want to use it to control the surround modes. What setting do I