Delta HMI usb update

I want to be able to store the History buffer on a dop-b series Delta HMI onto a usb. Bit 5 in the control flag register updates the usb data. I basically want to know, 1-If i set this to 1 every hour will that allow the usb to be written, 2-Will each time a write to the usb it over write old data or store it along side, 3-Do I then have to reset the bit to zero or will the auto flag reset do that?

Thanks