Recording previously recorded tracks on new tracks

I’m a newbie so please bear with me if these seem like silly questions. I had been recording tracks on my laptop with no issues. Because of location and practicality reasons I loaded Audacity on my PC record some songs. I had been using drum loops or a scratch vocal track I created on other projects I started on the laptop. Then I would record guitar, vocals, harmonica, what ever, tracks over. All was fine. But when I started recording over any of that type track on projects created on my PC all of these previously recorded tracks are being recorded with the newly created track ie, the guitar track I’m recording has drum loop track, scratch vocal track, etc, recorded with it making an audio mess. This was not happening on the laptop. Does anyone know how I can prevent this problem?

You’ve got the wrong recording device selected in Audacity. Go to the Edit → Preferences → Audio I/O menu and select the right Recording Device. Right now you’re set up to record the speaker output.