How can I copy application settings from one user account to the other on the same machine?
Most, but not all, applications save some settings in a .plist file in ~/Library/Preferences.

Look for and appropriately named file containing the name of the application in question.

Copy this file to the same location under a different User's Home folder.

Note that you may have to adjust permissions on the file for the other User Account to read/write to the file.