Not recording or playing back in stereo

I am using the Focusrite interface with a bluebird mikcrophone connected via USB. all indications seem to be correct but I am not sure. Here is why I am confused. If the microphone control on Audacity set to Focusrite USB, I will not record or playback in stereo. If the microphone setting is set to “Realtec High definition” it will record and playback in stereo. would this be a correct thing to do or am I doing something incorrect.

A single microphone is mono. A single voice or instrument is also mono. If you use a single microphone is stereo, you’ll generally get only the left or right channel.

A true mono recording will play out of both speakers or you can make a “dual mono” recording with the same sound in both sides.

I don’t know what the Realtek (built-in laptop mic?) is doing, but some laptops have more than one mic.

…If you have a 2-channel Focusrite interface and you only use one input it may max-out at half-volume (-6dB) if only one channel is used. If you record in stereo you can get full volume but you’ll have to deal with the silent channel by making a true-mono or dual mono file after recording.

Which Focusrite? The Solo is a basic, single microphone system and will mount perfectly Mono (one blue wave) with your voice coming from both left and right.

The Focusrite 2i2 is native stereo (two blue waves) and has trouble producing a good mono track to both left and right.