The Restore Default Options in the Options menu of the source view
  copies the system default debugger resource file
  DECW$SYSTEM_DEFAULTS:VMSDEBUG.DAT to the user-specific debugger
  resource file DECW$USER_DEFAULTS:VMSDEBUG.DAT.  It does not purge
  previous versions of the user-specific debugger resources file.

  You must exit and restart the debugger to invoke the default
  definitions in the restored debugger resource file.