Which type of free ticket changes (same dates, same origin/destination) are permitted by UA in the event of a 2+ hour change to departure or arrival time to one direction of a roundtrip flight? I do not want to refund and rebook, rather I want to book a (more expensive) routing without paying the fare difference.
-Am I permitted to make adjustments to both directions even if only one had a schedule change?
-Am I permitted to switch from a connecting flight to a nonstop?
-Am I permitted to use a co-terminal airport?