Can't select one single track in v3.7

I can’t select one single track or region.
Any action I take shown in the manual only selects all tracks in the recording.
If all tracks are selected, I can’t unselect the tracks I don’t want to process.
The selection of all tracks happens no matter what option I chose in Audacity’s Select menu.

I used to be able to select single tracks, or parts of tracks, with v3.7 it must be possible.

Any suggestions?