grabar sonido / record sound

Windows 10. Audacity 2.3.2
No tengo ningún problema para grabar si conecto los altavoces y configuro:
WINDOWS WASAPI HEADHONES HEADPONES
Pero cualquier otra configuración no me permite grabar. Si desconecto los altavoces, no puedo grabar nada, pero la única configuración que no me da mensaje de error es con WASAPI.
¿Alguna ayuda?

I have no problema recording if I connect the headphones and configure:
Windows WASAPI HEADPHONES HEADPHONES.
But I can’t record anything with other configuration.
If I discnect the headphones, I can’t record anything, but the only configuration that doesn’t give an error message is with WASAPI.
Help, please.

I tried to record a guitar on a backing track, but the BT and the guitar are recorded together on the guitar track. Before I could record the guitar alone and then join the two tracks by exporting.