The trigger sets the alarm trigger level.
unlike before, it now uses the blue sleep pattern graph as data source.
This should give a more accurate alarm.
If your blue bar is always too low, increase the value in the settings window.

Actually it should already be on a good level, unless you changed it.
I have it around 30..40.
Changing this value will also impact the display of the already done records.

Once you have set the blue bar, I suggest to set the trigger level around the top end of the grayish background bar, indicating "light sleep" in the graph.