Zirkzee scored twice in Sunday's win against Everton - his first goals in 17 games for United.
He admitted: "Obviously, the longer it takes before you get back on the scoresheet, the more frustrating it gets. But I have some great teammates who always keep my head up as well when I'm not keeping them up.
"They helped me a lot during that time as well. Today they were happy for me as well.
"Hard times great strong people and strong people bond. I think that's what's happening now. The most important thing is that we keep going."
On working with new manager Ruben Amorim, Zirkzee also said: "There are some slight differences. I got out there and tried to do what he asks me and expects.
"I felt comfortable in the role I was in. Of course, the goals help as well for a striker. We all came out with the confidence that we were going to win this game.
"A win is exactly what these fans deserved, so it's a great day. There were a couple of moments where it could've gone differently, but I think we stayed strong as a team and 4-0 was a great result."