Same, for years. I'm so tired of going back to preferences and having them not work. I do it about once a year just hoping in vain.
I use this free astute graphics plugin
DirectPrefs - Astute Graphics
You have to make a free account, download their unified installer and select DirectPrefs,
( perhaps best to deselect the paid plugins and trial them later one at at time later)
Basically its just a little window that allows quick change of the constrain angle without visiting the buried preferences every few seconds.
But the illustrator constrain angle seems to work with the pen tool +Shift but not the Line segment tool, which only loves 0 45 90 etc.
Also I added the red line to the black, but had to overshoot and later drag the anchor point back, after the blue line was drawn, as the smart guides don't always help find the meeting point, inference point or whatever its called.
