The Dutchman was pleased with how his squad coped with the tactical changes he introduced, with 20 players enjoying at least 45 minutes of action at the Rose Bowl in Pasadena.
Wayne Rooney, Ashley Young and Reece James all netted twice, while Danny Welbeck added the other goal against the leading MLS side.
In front of 86,432 spectators, United played a 3-5-2 formation, instead of the more usual 4-3-3 or 4-2-3-1 used last year.
And the 62-year-old said: "We introduced a new system that we have only played two times on the training pitch 11 v 11.
"But the boys are willing to pick up the information. It is fantastic how they have performed.
"Last week, 10 players who played tonight were not even in our training complex.
"When you want to change a system, you must start at once. We don't have time to prepare for other things.
"The other system they can play is 4-3-3 and they have played it for many years.
"I can change back if the system doesn't work. With the quality of the players we have, I can play 4-3-3 with three strikers on the bench, but I want to play with two strikers."
As for his current squad, he added: "We have four number 10s, so the selection is not balanced in my eyes.
"I have decided to play this system because of the quality of the players. But if we lose, I can change back to another system."
Regarding the one-sided victory, he went on: "The result always matters. With such a result you get confidence. It is fantastic how they have performed today.
"When you see us train, you can expect something but not 7-0. It was a surprise, but they were beautiful goals and beautiful attacks."
Ashley Young, who scored twice late on, as well as providing two assists, added: “When we defended we defended as a team, and when we attacked we attacked as a team.
“The new manager came in with new ideas and a new philosophy and you could tell that with the formation we set up with.
“I think everyone is warming to the philosophy and the ideas. There was a lot of space for players to get on the ball and LA Galaxy were unable to cope with that.
“We tried it in training and we tried it tonight and I think this will be the formation we take forward. We’re looking to get the ball forward and get it into the attacking areas and get goals and we‘ve seen tonight that we’ve managed to get on the score sheet seven times.
“It’s only been a few days that we’ve been on the tour since the managers came in so there’s plenty more work to be done.”