Why do the parking lights keep flashing after changing a car battery?

I recently took my 1997 Subaru Impreza to get a new battery. After they installed the battery, the parking lights flashed, and continued to flash, even after starting, moving, and locking and unlocking the doors. One mechanic suggested to use the remote lock and unlock device. We drove all the way home with the lights flashing, found the little wireless remote to unlock the doors, pressed the button and the flashing stopped. I was just wondering why the car would do that or what its for? Most of the people there said they have never seen it before.|||It was the security system needed to be reset. Very common when battery has been disconnected especially if secyrity was activated when battery failed.|||You were lucky the seller of the battery installed it. My problem was the alarm went off with the lights flashing and stopped only after I finished installing the battery. It%26#039;s just another feature to frustrate the vehicle owner.