I will not discuss case when user moves ScrollBar's slider.

First, set LargeChange and SmallChange properties to different values. LargeChange value is used when user click between slider and arrow button. SmallChange value is used when user click on arrow button.

Second, both clicks fires Change event, but in this event, dependent on where user was click (between slider and arrow button or on arrow button), Value property of the ScrollBar was changed from it's previous value with LargeChange or SmallChange value.