emac restores to factory settings when shut down

[LexiBalunas]

i bought an emac that was previously used in a school. i changed all the settings on the computer to my own and when i shut it down and turned it back on, the settings were restored to the original. i've heard that schools use programs to make this happen so it doesn't save anything on their computers but i'm not sure of the name of the application or how to get rid of it. if anyone can help me i'd greatly appreciate it.

 

[BlueRevolution]

Format the hard drive and reinstall OS X.