Bel 955 did not retain settings

I just pick up (very cheap) a Bel 955, but when power up it shows CD, and the settings are: city noX, vol is set to maximum level, auto mute on...(i think this are last stupid settings that previous owner made and the detector saved)When i try to enter in settings mode, it sound for 3 second as X band alert, but i manage to find that in first 2 seconds of power on, i can enter the settings, do my own settings, but it will not retain them. Anyone can give me a hint? (Bel service is not an option - Europe location...)
It works fine, detects K and x band (those 2 i can test)

I have not had my hands on a 955 in over 5 years, so sorry I forgot the settings and all

I did however Google the manual for this detector for you so this should help you: http://www.beltronics.com/manuals/v955manual.pdf

Thank you Roy for the answer, but my problems are not in manual...The detector keep starting with some strange settings, and when I change them, it just starts again with previous wrong settings.These is a common problem for M4 platforms as i can see on forums. Maybe someone did found a solution...