I'm using Acrobat Standard DC (2015 Release) on a Windows 10 Pro 64-bit OS. When I open dialog box at File>Create>PDF From Scanner>Custom Scan, the box is so large that I cannot see the "OK" and "Cancel" buttons across the bottom and there is no way to resize the box. I have found that I can go to Windows Settings>System>Display>Scale and layout and change from default 175% scaling to a smaller (custom) setting, but this makes all text, icons, and everything too small. Searching Adobe support, I found a similar problem with Adobe Muse that described resetting Environment Variable in Windows System properties for Muse, but that did not work for Acrobat.
In Acrobat, go to Edit - Preferences - General and select "Auto-Detect" under "Scale for screen resolution".
The Auto-Detect was already checked. I did choose the "No Scaling" option and found that the entire Acrobat Window had small font and the rest of my Windows Apps stayed at the 175% scale that is easier to read. So that may be what I have to live with.
If there are other suggestions to fix this for Acrobat, I'm open to try.