Check the sound setting on the computer by following the instructions below.
(1) Connect the DDJ-1000 to the computer.
Open [Control Panel] - [Hardware and Sound] and click [Sound].
(2) Check the sound setting.
If the DDJ-1000 is selected as default device, click a sound device other than the DDJ-1000.
Click [Set as Default].
(3) Close the Control Panel. See if you can change the volume of the computer speaker.