Hello BahamaCCTV,
The only way those settings change normally is because someone changed them. I am not sure it is plausible that a malfunctioning dvr or camera could change on their own. Obviously it happened to you somehow though. Depending on the firmware some dvrs let you change from PAL to NTSC and back again. That option was in the general setting. That is also true on some of the cameras they would let you change between formats.
