Lock layout?

Can I make a setting to temporarily or prevent a particular layout from being edited? In other words, can I lock and unlock a layout?

No: but realistically, nothing’s going to move unless you tell Dorico to change something.

What are you trying to achieve?

It’s a long story. You answered my question satisfactorily, and so I will take a different approach to the problem that doesn’t require locking a file. Thank you. I will explain it if you are curious.

It’s always best to explain the problem. That way, you get answers about the best method to solve the problem, not just answers about one method, which may not be possible/optimal.

Don’t forget that in Dorico you can chop things up into separate Flows; you can have multiple score layouts with different flows in them; so, there are plenty of ways of ‘localizing’ your edits.

Ok. I’ll tell all. You asked for it!
I’m writing for classical guitar. The work is a transcription of Bach’s Violin Partita II in D minor, BWV 1004, in this case the last movement, the Chaconne, a 257-measure Goliath that takes 14 minutes to play.
The violin plays many chords, sometimes on all four strings. The voicings are often impossible for guitar, and not always ideal for any instrument. So there is a lot of moving notes up and down an octave or leaving them out altogether. That’s the first task after copying the violin part, from the Bach-Gessellschaft edition, by the way.
Measure by measure, note by note I ponder, judge, and decide what to do. That’s when it gets dangerous while my septuagenarian eyes squint like Bach’s do on the cover of the book I’m using.
I put the violin in one flow and the guitar in the other. Not so good, so that’s when and why I asked about locking down one flow so I couldn’t inadvertently overwrite the wrong one.
After receiving your message I decided to delete one of the two identical flows and hire a violinist to sit underneath the guitar on the Full Score. Now I see guitar music and violin underneath, with cue-size notes just to be a little safer. This is a good solution, and your information helped spur me to go that way.
One extra refinement will be to make a “part” consisting of big guitar notes on top and little violin notes underneath, so that my enharmonic adjustments will show up as I want them to on the guitar part.
The last step is to add the fingerings, the glorious functionality that brought me to Dorico to stay. (Sibelius? You mean the composer, right?)
That’s probably more than you wanted to know, and I thank you for your help and indulgence.