Record button creates new mono track when already in new stereo track?

I frequently work with Audacity, finding it quite useful to create sound bites and such, and am also a musician looking to use to it work on new material. However, my Audacity seems to have a mind of its own tonight. Hopefully someone here knows what is going on – I suspect I may have inadvertently activated a hotkey, as my wireless keyboard loves to slide off my lap and into the floor. Anyway… to the problem.

Up until now, the software would wait until audio was detected on whatever track I was on when I pressed record. But tonight, it has started creating a new mono track independent of the one I wanted to record to. WTH? I cannot figure this out to save my life and it is annoying beyond words. Have I inadvertently activated a macro through a hotkey combination I didn’t know about?

Set the required number of recording channels in the Device Toolbar.

Audacity has two ways of recording:

  1. “Append record” (default) - record to the end of the current track if possible.
  2. “Record to new track” - creates a new track and records into it.

By default, clicking the Record button (or pressing “R”) will “append record”, and “Shift + Record” (or “Shift + R”) will record to a new track.
There’s an option in “Edit menu > Preferences > Recording: [_] Record on new track” that changes the default to “Record to new track” (then “Shift + Record” will “append record”).

If you record 1 channel into a stereo track, the same audio will be recorded into both left and right channels.

It is not possible to record 2 channels into a mono track, so if you try to “append record” 2 channels into a mono track, the first (left) channel is recorded into the selected mono track, and the second (right) channel will be recorded into the next mono track if one exists, or will add a new mono track for the second channel.

More info here: https://manual.audacityteam.org/man/recording.html