I’ve just finished working on editing horn part lay-outs and had to do a fair amount of clef changing for the transpositions to sit on their staves comfortably. But now that I’m done with that, I see that the clefs in the score (which is in C) have changed. I thought that the editing of clefs and such carried out on the part lay-out did not affect the score.
Items exist in all layouts, but you can set clefs not to appear in concert or transposing layouts.
If you want a clef change to appear at the same position in all layouts, but show e.g. treble clef in the transposed pitch part but bass clef in the concert pitch score, see here: