If it asks to set the date each time you turn it on, you need to replace the date battery CR1220 which is used to power the clock while the camera is turned off. Main batteries are not used for this purpose so as soon as you turn off your camera, it will forget current date if CR1220 is discharged. Usually CR1220 can last for few years, so many users are not even aware it exists. Replacing it is very easy, just follow these official instructions: https://support.usa.canon.com/kb/index?p...