How do I chanec the size reduse size. from the preferance?

[boba44585016]

I've 2020 element PS.I looked at the image Most of the time I chose the size reduse size. How do I change it from the prefance. 

[Phinny]

Your question isn't clear but the answer depends on your purpose.  If you simply want to control how it displays on screen, you'll find options for that in the Zoom Tool settings bar.  Also see "Learn more about: Image size" as shown in your screen shot.