Sir Alex expects to sign a new contract to stay on until the end of next season within a week.
"Perhaps we lost our unity when I announced that I would be leaving front-line management at the end of the season," he wrote in his programme notes for Sarurday's match against Aston Villa.
"Certainly we had a rocky time earlier in the season. Maybe the timing of my announcement that I was seeking a different kind of job with United was wrong, although I don't think my motive was.
"I simply wanted to give the club time to find the right replacement.
"But it is in the past, at least for the next three seasons, and we are all united again.
"I know exactly where I'm going and I hope my decision will make it easier for our players to travel the same road with a common purpose."