This seems absurd, but I can’t solve it. I want to disable the colour display of notes out of range (because I’m using Dorico’s instruments for purposes they weren’t designed for 
and the display is irrelevant). I go View > Note and rest colours and highlight Notes out of range, but whatever I do—click, return, space—that item remains checked and the out-of-range notes remain coloured. What obvious step am I missing?
I just tried and it seems to work here. Can you attach a file?
I can’t attach the file I was working on, it’s a composer’s work in progress. But I don’t believe it has anything to do with the file. Here’s a trivial file with the same problem: I’ve raised the first phrase to an absurd pitch, the notes are shown in red = out of range, and I can’t switch off this display.
I’m using Dorico 4.2 on Windows 10.
All the way from Manchester.dorico (550.1 KB)
Thanks for the file. It works here still…
In View > Note and Rest Colours, instead of choosing Notes Out of Range, have you tried choosing None?
Oh damn, I didn’t even think of checking about that 
Choosing None does indeed get rid of the out-of-range colour. Thank you! But I don’t think that’s the way the UI is meant to work—at least according to the Operation Manual.
Some commands are toggles - select once turns it on and selecting it again turns it off.
Others have a separate command to invoke the opposite effect.
I just had a quick read and I guess you are right. Although, None is in the same menu as Notes out of range, which you could argue indicates that you select it if you want none.
The Operation manual (p1077) says:
Procedure—Choose View>Note And Rest Colors>Notes Out Of Range
Result—Colors for notes out of range are hidden/shown.
The latter sentence clearly implies this is a toggle, but evidently it’s not.
I agree – @Lillie_Harris, this should be made clearer. The first 3 submenu items are a one-choice set, like radio buttons, and all the rest are toggles. Not clear from the menu itself.