Fernandes, also club captain, was apologetic when previous boss Erik ten Hag lost his job.
Interim manager Ruud van Nistelrooy ushered three wins out of four, but now Amorim will be tasked with reviving United.
Fernandes said: “I hope he does the same here because, you know, sometimes a person can change the energy of a space, if it's the right moment.
“We hope that he can come and that this is the right moment for him to come and bring his energy, bring his qualities and his knowledge of football, because he's done something really, really special at Sporting.
“If someone doubts that, it's about just looking at the past. Sporting was about 20 years without winning the league and he got them back to winning the league.
“He won it two times in four years with a really youthful team, in a moment of change. So hopefully he can do the same here for us and hopefully it's going to be a successful time for all of us.”