Garmin Segments: how to know before a ride which segments are going to trigger during the ride?

I am quite new to Garmin and I am still trying around how Garmin Segments work.

For now the only Segment that triggered on my Edge 130 was the one that I created myself from an earlier activity of mine, marked as favourite and uploaded onto my Edge. However, other Segments that were not created by myself do not get going during my rides, even if I mark them as favourites and had already travelled across them earlier on, and it is only after the ride that I see that I actually did travel along it.

Is there a way to make sure that a given segment is set to appear on the Edge during the ride? Note that I am usually following a predefined course. Also: my Strava Account is connected, but I don't use Strava Segments and I already made sure that the Segments that are set up are the Garmin ones.

Other question: what would happen if two segments overlap? Will the second one not get going at all, or will it start in the background and appear after the second one has finished, or will they be visible both of them but on different pages?

Thanks in advance.