Kind of moot because the time traveler wouldn’t change events in his own timeline.
You can’t change the events. You can only change your own personal reaction to those events if you happen to be fortunate enough to have the memory of those events.
I don’t know about being able to step backwards, but I have reasons to believe that stepping forward is possible so that when you step backward, you come to your present reality. Haven’t an IOTA as to what controls it.