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  Please do not worry, I am here to help you. The issue can be solved easily. :-) If you are connecting the device with Dolby sound feature(like DVD player, amazon fire stick, Xbox, PS4, etc), please remember to close the "Dolby sound option" of the device(not the projector, just the device you connected), or there will be no sound. The reason is this projector does not support Dolby's Audio decoding due to the copyright of Dolby, so you need to close the Dolby option of the device, you will have the sound. How our customers close the Dolby of the fire stick: setting-->Audio, then select "Dolby Digital plus OFF". For cable box: set the Audio Output of your cable box from "Auto/Dolby" to "PCM" , then reboot it and connect it with the projector, you will have the sound. The Dolby setting must be in the Audio/Dolby settings, it may also be this option "Dolby Digital plus OFF". Link. https://www.amazon.com/ask/questions/TxKHPZRQY7L48