What makes the data to scroll in LED matrix display?
The shift registers are used to actually address/control each of the many LEDs with a limited amount of microcontroller pins.

However, what these shift registers shift around is controlled by the microcontroller. It calculates which 0s and 1s to shift in and will just calculate how each displayed frame looks like.

The microcontroller is the "brain" of such displays. Shift registers are just the "fingers".