Garnacho was sold after falling out with then manager Ruben Amorim.
Asked if he had regrets over the reasons for his departure, Garnacho told PLP: "Maybe yes, because I loved that club.
"They gave me the confidence from the start, from Spain, to bring me to the academy, then they bring me to the first team, so it was like four or five years, and amazing love from everyone, from the fans, the stadium, everything was really good.
"It's just sometimes you have to change for the good of your life or the next steps. I only have good memories of Man United."
The Argentina international then said: "I remember in the last six months I was just not playing like before at Manchester United.
"I started to be on the bench, it's not a bad thing, I was only 20 years old, but in my mind it was like I had to play every game.
"In my mind, maybe it is also on me, I started to do some bad things. But yes, it was just this moment in life and sometimes you have to make decisions and I am really proud to be here and still in the Premier League at a club like this.
"Everyone knows the team we have and the things we can do. Sometimes, we have better moments or worse moments, I am proud to be here but with United, I have nothing wrong to say about the club, no one in the club or the team-mates. It's just a moment in life that changes and life continues. I have no regrets."