I was a passenger on a United Airlines flight from Hawaii to Sydney some years ago, on a 747SP.
Just before pushback, they announced a trim problem, and needed volunteers to move from economy to Business class! Being quick on my feet, I made it to business - all well and good.
Once the take-off was completed though, they dragged all the volunteers back to economy!
For the landing? Yep- moved us all up again.
Now if the aircraft was out of trim for take-off, and out of trim for landing, what was happening during all those hours of cruise!!