Audacity plays and records at the same time

Hi all, I am a Newbie. I recorded a track and then fumbled around a bit and now when I hit record it starts a new track underneath my first one and plays the first one at the same time while recording the new one. How do I stop this? I don’t want to hear any other track while recording!

Which version of Audacity are you using? (look in “Help menu > About Audacity”).
The current version is Audacity 2.3.2 and is available via the Audacity website:

In the current version of Audacity, pressing the record button will, by default, continue recording from the end of the current track, rather than starting a new track.