For any questions about usage, please don`t hesitate to send them to us through Amazon. Here are some of the problems encountered and solutions. P: There is no sound coming from the speakers when playing back video? S: The“record audio” in MENU needs to select "ON", and when playing video, the lever on top of the camera swings in the "W" direction to amplify the volume, and 10 is the maximum volume. If an external microphone is connected, the built-in microphone is turned off and won't record sound. This external microphone switch must be turned on, if not, it is equivalent to turning off all the channels for recording sound. P: The camera gives us an error message that the cards are unrecognizable or have not been inserted. S: This camera supports up to 128GB SD card, if it is larger than 128GB the camera may not recognize it.