Allow Bluetooth permission when asked so the app can scan for your headphones. Or turn on the access permission in Settings -> Bluetooth later.

Press Red Button on the main screen to scan all Bluetooth devices nearby.

After scanning is complete, the app will ask you to select the device you've lost. Remember you can’t locate turned off devices, and some devices that are already paired with some other device.

Move around and watch for the meter as you get closer or further away.