FWIW, the scale is a Scaled Drawing object so you can just right click on it and choose the desired scale in the list. Or do that via the Scaled Drawing panel in the tray. You might need to change the font size for the numbers depending on the scale you select.
A little off topic but another FWIW: If, after clicking to set the second anchor point for your dimension, you hold Command (Alt on PC), you can drag out the dimension so the extension lines are vertical instead of being angled.