Here's a link about that. http://www.scribd.com/doc/12736526/Samsung-LN46A650-LCD-TV-Manual
Page 15 notes the Store Demo mode. You want to change that.
My Samsung LN46a650 picture keeps resetting to factory default setting after about 20-30min. I check the firmware and settings and didn't find anything. I also moved remotes in case one was sending some type of picture reset command. Does anyone know why this maybe happening?