Octave lines not on certain layouts?

Is it possible to have a setting for certain layouts (flutes/Eb clarinet/violins for example) to never show octave lines in the parts when they are set in the score? I seem to remember they can be overturned manually but can’t find that setting.

Indeed, clefs can be set individually to appear in parts or in score (or both). I suppose if you right click on the octave line>Clef, you should find those settings.
Edit: I’ve just checked, and it appears what I’ve written is plain wrong. What you can do for clefs (and clefs only, not octave lines) is choose which clef appears in a transposed environment vs in a concert pitch environment (which could be parts vs score but not all the time, obviously !)

Thanks, Marc. That must have been the function I remember but most have been lost in Dorico 4.

I am quite sure it is not true. The only things we really have lost for a certain time are features in Play mode that are being rebuilt, and we’ve recovered already most of them…

No, there’s no way at present (and nor has there yet been to date) a way to tell Dorico to show octave lines only when the score is at concert or transposed pitch, which would be the equivalent feature for octave lines to complement the existing functionality for clefs. We would like to add this at some point, but I can’t say when it will be done.