Thank you everyone for all those good advices. I tried he New Part method, it works fine, but then I need to copy the first part with the mirror tool to be still able to edit it, and I am not so...

... And is it possible to use different staff attributes for score and parts? Like hide/show chords, lyrics etc

I have somehow a similar probem. In my score the tuba part is written in Bass Key, without any transposition. But I made this part for a tuba player that is used to read in Treble Key and with Bb...

The point is not to automatically transpose any note, but to have the choice to do it. For example I have now a tune in F, some bars including a C7 chord for a guitar. Later in the same tune I change...

I would need this feature every day. I can only agree with Ere, this is one of the typical non user-friendly defaults in Finale.