Camera motion alerts are turning on after being turned off

We have had a number of cameras working for a year. All of a sudden both yesterday and today all of them had the Motion Alert turned on when they had been off forever. We have not touched any settings so we have no idea why this is happening. Is there something we can look at to see why this is a problem all of a sudden. Also, is there a way to turn off all motion alters for all cameras from one place rather than going in to each one to turn motion alerts back off?