Amorim has had a rollercoaster ride since succeeding the sacked Erik ten Hag at Old Trafford.
United enjoyed a late comeback win over local rivals Manchester City only to then slump to a 3-0 loss at home to Bournemouth last weekend following a midweek 4-3 League Cup quarter-final defeat by Tottenham.
Rashford was omitted from all three of those games, with the 27-year-old, a product of the United youth system, now looking increasingly likely to leave Old Trafford.
The struggling England international fuelled speculation about his own future by saying he was "ready for a new challenge" in a midweek interview.
But Amorim, speaking ahead of the Boxing Day match away to Wolves, said nothing had changed from his point of view.
"Normal situation," he said. "When I feel that it's the right moment I will change something. Until then I will continue to think what is the best for the team.
"I speak with him (Rashford) every day. Not about the interview, about the performance."
Amorim added Rashford "wants to play, he is trying" but "it's my decision, only my decision".
"I spoke with a lot of players -- individually, during training -- so I'm trying to do things... I am doing things my way," the Portuguese boss said. "And it's the only way I know.
"If I don't do that I will lose myself and I will not lose myself. I know what I'm doing."
Amorim questioned the "choices" of people surrounding Rashford after omitting him from the Bournemouth match, when Gary Neville said the forward leaving felt like an "inevitable ending".
The former United captain also called it a "distraction for the manager" -- something Amorim denied Tuesday.
"No, I don't think so," he said. "Not for me, not for the other players because everybody is there every day during training, so they understand and that is the key point.
"For the media and for the other people, I cannot control that.
"But I'm really focused and they know, I'm so clear in my message, everybody in Carrington know what I'm talking about and what I want from Marcus and everybody else.
"So, it's not a distraction for us. Maybe it's for the media but that is not my concern."
'Responsibility'
Amorim, asked what more he would like to see from Rashford, replied: "Like any other player, the best that they can be.
"If you have big talents, big performance, big responsibility, big engagement, like push forward everybody in this moment. And some guys have a big responsibility here because they are here for a long time."
United are a lowly 13th in the table ahead of Thursday's match against a team managed by Amorim's compatriot Vitor Pereira, who is taking charge of his first match at Molineux fresh from leading Wolves to a 3-0 win at Leicester.
"I understand that it's a tough moment, and it's on me," said Amorim.
"Since the first day that I arrived, it's on me because I'm responsible for the team...We just have to think about improving, to understand the context and not focus on what happened in the past."
