I'm trying a very simple set up, with an electrical signal in CH1, trigger in CH1 at 1V, and the enabling the "trigger" setting makes no difference. It keeps on updating the display as if it were not checked.
I tested the Android and the pslab-desktop app, and also the pslab-python alone (with the oscilloscope capture() trigger parameters and also with configure_trigger()).
Maybe it's a bug in the PSlab v5 board or firmware? I bought the board some years ago. I don't know if I can check or update the board firmware easily.