If your TV has a headphone jack or variable analog audio output you could connect a BT transmitter to that. It would allow some range of adjustment with the TV remote. If the speaker has an aux input you can connect it directly.
Most TVs won't let you use the internal speakers at the same time as you use the audio outputs. Check your manual or try it. You may have to turn the audio output on in the TV menu and adjust it to get it working.