The 59-year-old was fired the day after that defeat, having had only one full season in charge, and told reporters on Tuesday that he felt before that game that only half the team had faith in him.
"Many things have changed since then, PSG have changed coach for example, whereas at Munich the problems have still not been resolved," he said.
"My mood has changed a lot. Last year when I came here, I felt I had the trust of only four or five players, now I feel I have the confidence of all the players and everyone around the team. That has changed my frame of mind completely."
Ancelotti was appointed my Napoli in May, returning to Italian football after a nine-year absence. During that time, he spent two seasons at PSG, winning one Ligue 1 title.
"I have good memories of my time here, I improved my knowledge," he said.
Napoli lead Group C with four points from two games, one ahead of Liverpool and PSG before Wednesday's games.