The color of text cannot be changed in the current version of musescore
Just started using the program and the little intro composition you see gives you a bunch of notes in coloured text, its useful to have coloured notes for a band to not get confused. Yet the "color" box in the inspector does absolutely nothing to text
Comments
It sounds like you have notes out of the instruments' ranges. You probably have the wrong instruments selected. If you attach your score and tell us what you expect someone will be happy to help you.
See https://musescore.org/en/handbook/3/note-input#coloring-of-notes-out-of…
It's not clear if you are talking about coloring notes or coloring text (maybe you used the word "note" in the generic sense, as in "a short piece of text"). But anyhow, the Inspector definitely work if you use the color picker correctly. Details different between Windows, macOS, and Linux. So if you're having trouble, please attach your score and describe precisely step-by-step what you are doing, and we can help.