Solution:
- Launch QuarkXPress 2015.
- On Mac, navigate to QuarkXPress>> Preferences>>Key Shortcuts.
- As displayed below, edit the shortcut for a specific menu in the shortcut column.
- To save the user specified shortcuts, click on Make copy when prompted to name the customized key shortcut set.
- Once you add the name to the shortcut set and click OK, the shortcut set will be saved and will appear in the Key Shortcut Sets list.