Amorim fronted up to the press after his team were beaten 3-1 by Brighton on Sunday.
United lost yet again at home in the Premier League, remaining in the bottom half of the table.
On saying that his players have to suffer, Amorim explained: "It's hard to explain. We have to acknowledge the moment and not go around the problem.
“Everybody here is underperforming. No matter the circumstances, we are underperforming and we have to accept it is unacceptable to lose so many games…for any club in the Premier League, (let alone) Manchester United.
“It is a really hard moment but we have to continue. There is no other way, we have to suffer and continue."
On what he learned from the loss, he added: “The opponent is better than us in many details, that we cannot be consistent, that I am not helping my players in the moment. It's a hard moment and we have to acknowledge we are in a very difficult situation, all the bad records - losing games at home, losing games in the Premier League. We are really underperforming and we need to win games, that's all.”
On him saying that he is not helping his players, he added: "I knew it was going to be hard to put in a completely new idea in the moment. But when you lose games, you don't have that luck to win three games in a row, it's becoming really hard.
“That's why I'm telling (you) we are going to suffer because I'm going to continue to do the same. To help my players is to give them the tools to play this way, but, without training, it is really hard. Then, without training and losing games. You could feel it in the end of the game, everybody was changing position, and that is something I will not see again. We can lose, but we will not change position.
"I just want to help my players. If I want to show to the media and the fans, I (would) put two strikers (on the pitch), I didn't put two strikers (on) because it is going to be more difficult for them to understand the way we play. I'm just here to try to help my players, but we need to understand that we are breaking all the bad records. It's a bad thing we need to change."