How do you change the default paper type when creating a pdf using the scanner?

I have Adobe Acrobat X  Version 10.1.16

Open the "Enhance Scan" tool and start the scan. Click on the gear icon next to the default settings. You should get a new window that has options for setting things like color mode, resolution, paper size, etc. You can also save the new settings. This if for Acrobat DC.