Fortnite with controller on Pc voice does not work?

I play Fortnite with friends. If I want to play with the controller on the PC my friends can no longer hear me, neither can I hear them. But when I play with the keyboard everything works. Why is this and how can I fix it?

Have you connected the headphones to the (possibly Ps4) controller?

Your audio input and output has probably been automatically switched to the controller. You can set your standard devices in sound settings and then as input and output.

Ne I left the headset on the pc