As the title says, I must do it at every start.
My laptop has two output ports, one for each. What happens is that when I connect the speakers it tells me that they are headphones, and when I connect the headphones it tells me that they are speakers so I have to change it manually. With the built-in speakers, I don't have any problems.
If I change the port device I have to invert it as well.
I do this from Lubuntu 19.04 via pavucontrol-qt.