Fouad Bachirou and Peter Weatherson were among the goals for Morton.
And Fitzharris, 19, admits he was just glad to get back on to the pitch having spent a number of weeks out due to a hamstring injury.
He said: "It was good to get back out playing again because it feels like ages since I last played a game.
"But I managed to play the full 90 minutes so that was good and I don't feel too bad after it.
"It was a good game but for me it was just good to get out there after having been out injured for so long."