For example as starting point for discussion:
(avoid colision = on):
Now here are some problems if I want to change something:
1 .transpose:
2. change something before 01:
3 change something before 02:
Is there something I’m missing? or you have to readjust the line with the arrow each time in engrave mode
best regards
Dorico knows where things are “supposed” to go. When you move them in Engrave mode, you don’t put them in an explicit position, you set offsets relative to their “home” position.
If that “home” position later changes or the context changes, then the offsets become applied to the new “home” position, which might well result in them appearing at a different co-ordinate on the page.
In general, you’ll save yourself time if you try to leave minute adjustments until you’re as finished as you can expect to be with changing the musical contents.
Or, disable collision avoidance for text items, so they at least aren’t also contributing to how much other items move about. As discussed in your earlier threads 
Here specifically, how have you input that arrow? Have you tried inputting it with a notehead-attachment on the left, and a rhythmic position attachment on the right, so that the arrow part knows it’s supposed to be next to the middle note in that chord? So if the chord moves/transposes, the line will move with it?
(This is where sharing the project vs a picture can be helpful: so people here don’t have to guess at what you’ve already done)
@Lillie_Harris
Thanks again…I will test after 2-3 students but in the meantime I noticed that it seems to work if I use vertical rather than horizontal lines
(This is where sharing the project vs a picture can be helpful: so people here don’t have to guess at what you’ve already done)>
I understand that you would like me to post a project, but there is no point in posting a project because it is not a particular case just 3 beats with a chord in the middle and two texts and a desire to put an arrow to explain something for students for instruments in C, Bb, Eb: nothing particular and specific: just something that I would like to do every time I give a lesson.
Here specifically, how have you input that arrow?>
I just do it intuitively like in the following video (look the entire to see the transposition) and this way with the horizontal lines, it doesn’t work even when changing options in “horizontal lines” reverse, horizontal start,horizontal end:
But it doesn't matter at all: this is not my first failure and waste of a lot of time with this program which does splendid things
So solution for me for the next time: I can do this intuitively using vertical lines instead:
Thanks again
“Intuitive” isn’t necessarily going to be the best solution long-term, especially if you know you want to copy/paste such examples and transpose them.
A vertical line might work, but you might want to try adding the text to the end of the line, rather than having separate items all floating around.
I’d also recommend positioning your vertical line natively as close to its resulting end position as possible (meaning, on the right of the chord), again to reduce the likelihood of it ending up with odd collisions later if you duplicate it and change the notes.
Take a look at this alternative and you can tell me (or just think it privately) whether this looks like a neater, simpler, quicker way of producing what you want:
This uses the available tools for designing custom lines, and using appropriate attachment points. Takes a little longer to set up initially, but is more robust and flexible in the long-term. I leave it up to you now
Sorry to hear that – Dorico is a very powerful tool, it can just take some getting used to how it works to work out how best to get to the end result you want. Sharing your projects and asking for help here is probably the best way to get on the right track.
@Lillie_Harris
Ok great thanks : I succeeded with your method. super!
So I change my point of view :):
I’m afraid on the other hand of having a lot of elements in the right part and that the list will quickly become long… can we remove lines that we don’t want to lighten and save by default?
Concerning my frustrations, lost of time and intuitive thinking for the program I will write to you in P.M because I am afraid that if I write here it will go to waste and that it will generate a useless dialectic competition
Best regards
No, you can’t delete factory default lines. However, your custom lines should appear at the top.