Since I started watching, I have known the club for having a particular style of football and that is wing football. Every club has their ideology and every coach also has theirs. Amorim has enjoyed a lot of time and support from Manchester united, it is time he started producing result. He got quality players and has recently signed a goal keeper. There are no excuses not to perform anymore.
This is not also the time to be so rigid, if the formation that worked for him in Sporting is no longer working, there is no crime in trying new strategy. EPL is so dynamic and doesn't require high level of rigidity.
If Amorim can't fix players in their right position I don't think the results will ever change in a hurry and the wings you talked about can be or has been effective more but I think the formation he should use is the one that will balance how they want to play because if you look at how fast the wingers are at UTD you'd say they don't need to be lacking goals.
A
4-3-3 formation would suit the team pretty well and that can make Bruno to function properly and the striker Benjamin Šeško even the likes of Amad can sometimes come in as a sub for either Cunha or Mbeumo and the awaiting results I mean positive ones will start coming. Maybe Amorim still feel he's coaching Sporting CP in Portugal that's why he always use that same formation with his current players at Man UTD or he doesn't believe in change.