LG TONE Style TONE-NP3C Owner's Manual page 8

Multiple Connections
The headset can be connected to two devices, such as a smartphone
and a PC, simultaneously.
To connect multiple devices, turn off the headset while the product is
connected to one device.
Perform 1 to 4 under "Fast Pair." This device becomes the "Main
Connected Device."
Try to connect to headset using a previously connected device. This
device becomes the "Sub Connected Device."
NOTE: If the headset is simultaneously connected to two devices, the
main functions work based on the "Main Connected Device."
Automatic Reconnection
If you turn on the headset, it will automatically connect to the most
recent device (Main or Sub Connected Device) it was connected to.
(If a device cannot be found, Search mode will be activated.)
If the product does not automatically connect to the device you want,
search for your product on the device you want to connect to and connect
it manually.
6