Switch mode: when play music(USB card/ TF card / LINE IN/ BT), press short to switch USB/TF/FM/BT.(switch to "line in" if via AUX cable to audio device).
When play music(USB card/ TF card/LINE IN/BT), press short for "play/pause ", under BT mode with mobile paired ,press short to answer a call ,press again to hand up . press long to open/close the blue decorative light. in FM mode, press short to search station automatically, press again to stop searching)
When play music , press short for last song, press long to turn down the volume.
When play music, press short for next song, press long to turn up the volume.