I have a Samsung HT- E4500/ ZA Home theatre system and everytime I play a DVD movie when someone talks its muffled any ideas?
That is what you can expect with any home theater in a box.
HTIB systems don't perform as well as proper separates that can sometimes be purchased for about the same price. Try increasing the relative level of the center speaker. If it is already at maximum, decrease the relative level of the front left and right speakers.
Try increasing the volume for the center channel and decrease the volume for the front right and left...Also your center channel speaker needs a clear view to your ideal seating position no obstructions...If the center channel is recessed into a cabinet bring the speaker out more toward the front of the cabinet, you should be able to see the speaker from your ideal seating position with out obstructions and it should be pointed in the general direction of your ears while in that position.
Increase the volume of the center channel in the setup menu. You may have to decrease the volume of other speakers in the setup menu, as well. Use the main volume control of your unit to adjust the general system loudness over all.