Can anyone tell me where unix stores its password

Can anyone tell me how to know how to prevent the changing of password in unix. We works on a unix server through telnet on terminals. Anyone of us changes the password and the whole blame goes to me because people knows my habit of R&D. So please can anyone tell me how to restrict this. Thats a big problem of me. "Please mujhe bali ka bakra banne se bacha lo."