Feedback howl round on internal record

Have been successfully using audacity to record sound from you tube videos and other internal sources on my computer. Today I am getting horrendous feedback every time I try. I may have inadvertently adjusted a sound setting on the laptop. Have reloaded audacity and am set to windows wasapi - any ideas

Disable [u]Software Playthrough[/u]. (It’s so you can listen to whatever you are recording, but it creates a feedback loop when you are recording the sound coming out of your soundcard.)

Thank you so much that’s sorted it !