Middle-C position doesn't move key signature

[Johannes Roeßler]

Hi,

neither the clef position (which is mentioned in the documentation, so 
this is expected) - nor the middelCPosition move the key signature.
How do I have to move it?
\version "2.24.0"
{
  \key f\major
  bes'2

  \key c\major
  bes'2

  \set Staff.clefPosition = #1
  \set Staff.middleCPosition = #-3
  \key f\major

  bes'2
}

Cheers
Joei