Firstly, if you see the little “head” icons on the left of each instrument, you’ll notice that some have one head (= solo player) and some have two (= section player). Mostly, the type of players holding these instruments should be solo players unless there’s a specific reason for making them a section player, such as maybe for a concert band etc.
Secondly, and without seeing the instrument(s) that your Flute player(s) is holding, it sounds like you’ve using only one flute for the Flute player and you are using two voices to write two different flute parts? If so, you’ll need to expand the player, then click the three dots to the side of the instrument and select Edit Names. Now you can edit the instrument name and it should adjust in the score.
If you do have two flute players playing different parts, it might be worth considering creating two different flute players, each holding a flute, and use Condensing to combine them into one stave?
The advice is good if you need separate parts. But you can change the name of the instruments to whatever you want in setup (including numbers) without adding staffs or anything if that makes sense for your piece. Name it 2 clarinets, 76 trombones, 19 contrabass
Aha. I have figured out how to rename the setup (at first I thought “rename” was greyed out but after fiddling it lit up) but that is not reflected in the score
What will you do with this music once you have finished it?
If you mean to have it played by live players, you will need a separate part for each (say) trumpet or trombone, etc. In that case, in the long run, you will do best to follow customary Dorico practice and assign each player to a separate staff and use Condensing to combine them for your full score.
What you’ve done here is rename the Player rather than the Instrument that they are holding. The Staff Labels to the left of the staff list the Instrument and not the Player.
What you do is click on the > which is just to the left of the name in setup, then click on the … ellipsis that will appear to the right, and you will see edit names.
In case you wondered this is one on those times when the difference between instruments and players become apparent. With this procedure you are renaming the instrument, not the player. The player could have multiple instruments and be named “percussionist 1” or “keyboardist”
Yes, as @Derrek says, you need to ‘start again’, really. Create Single Player instruments, not Sections; and make 2 Flute Players, 2 Oboes Players, 2 Clarinet Players, etc.
Then let Dorico “Condense” them together in the score, while providing separate parts. Dorico will then write “Flute 1 & 2” for the Staff Labels.
Condensing is one of Dorico’s unique features that will save you huge amounts of time and effort, if you take advantage of it.