TS3 does not work with a second screen?

I downloaded TS3 a few days ago and then found that the sound wasn't working. I then tried something out to see what might be the cause and found that no matter which audio output I select, no sound came out. Yesterday I noticed that this is only the case when my screen is connected (I always connect a larger screen to my laptop, but so far I haven't had any problems with the audio). The screen has neither microphone nor speakers, but strangely enough it still takes the microphone from the laptop. So the others hear me, but I don't.

This is probably because the one (nonexistent) speaker is looking for the second screen. In the TS settings, however, switching to the other loudspeaker does not work. Headphones or external speakers don't work either.

Do you maybe know how I can fix this?

Under Tools → Options → Playback → Playback device you can choose between standard and your computer's sound output.

Test around in the area.

I did that. There are two other possibilities, but unfortunately I didn't have any sound with any of the three.

But otherwise does the sound output work with other programs?

Yes, for example Teams, ITunes and Youtube work.