|The DVD sound probably has a different volume control you need to adjust in the sound mixer settings. |
See Response 6 in this
" Make sure you don't have volumes set too low or muted, for things you want to hear or use.... "
The DVD supports 5.1 sound, but your laptop's audio chipset has to support 5.1 sound too in order for you to hear 5.1 sound.
If the laptop has only one sound output port, it can only support stereo - 2 speaker - sound.
If it has more than one sound output port, the jacks for the speakers must be plugged into the proper ports, and you must go to Control Panel - click on the icon for the brand of sound adapter, and set it to 5.1 sound - it's set to stereo - a single pair of speakers - by default.