How to change the scheduled workout

So I have a bit more time than usual to ride tomorrow and I was going to change my plan. Currently, my plan is set for a 1:15 VO2 workout but I’ll have about 3 hours instead. To change the workout planned do I just go into the workouts and pick a workout for that time frame, also would AT still recognize and track this change of the plan?

Follow this article for best practice.

Would it still track adaptions if you don’t use one of the alternatives but swap it to a different zone I.e. tempo or endurance?

Yes, it will impact the related zone and change your PL assuming it’s above your current PL for that zone.

If you miss or skip the other zone, AT may lower the pending workouts on your calendar that match the skipped zone workout.