Dear ClareBadcock,
Thanks for reaching out! I'm an Independent Advisor and a Microsoft user like you. I will be happy to assist you in this regard.
As far as I understood your question, The color of the desktop icons would not be changed when you change the color from Personalize > Colors. Is that correct? If yes, The desktop icons color will not be affected by changing Colors. See the attached image, Just Start, Taskbar and the top bar of File Explorer will be changed.
However, you can change the app Icons by right clicking on it > Properties > Shortcut tab > Change Icon.
Or, you can change the Desktop Wallpaper to Solid by right clicking on the desktop > Personalize > Background > in the Background options choose Solid.
Please let me know if you need further assistance and keep me updated.