The mac-only "Duet 2" model's settings are saved on the computer rather than on the device like later "Duet for iPad & Mac" or Duet 3. Your computer may not have given the Apogee Control 2 app permission to write to your computer's drive to store these settings. Here's how to fix it:
- Open Mac System Preferences > Security & Privacy:
In the "Privacy" tab, select Full Disk Access from the left-column.
Click the lock icon to allow changes.
Then on the right, make sure the box next to Apogee Control.app has been checked:
Restart the computer, and test if the settings are now saving.
The settings are stored here on MacintoshHD > Library > Application Support > Apogee > Settings. Once permission to write to this folder is given, an XML file for DuetII should appear in this location: