If you are experiencing unexpected issues such as short work range, audio cutting in and out, not pairing, etc. you may need to clear the paired history of the HT4186 headphones and transmitter.
Clear the paired history of the transmitter:
After power on, press and hold BOTH A and B together for 7 seconds, both will be on BLUE for 2 seconds, then A enter pairing mode automatically, close to A flashes RED and BLUE alternately.
Clear the paired history of the headphones:
After turning on, press and hold both “+” and “-” for 10 seconds until the RED and BLUE LEDs are BOTH on for 2 seconds (looks PINK) - now all the paired history of the headphones is cleared. It then enters pairing mode automatically with the LED flashing alternately RED and BLUE.