Can't change icon sizes on 12.3 desktop

I just recreated my 12.2 install on a different partition using 12.3. My identical desktop on 12.3 has icons with 4 different sizes. I've found no way to correct this and have a reasonable looking desktop with icons all the same size. I've found no way (that works!) to alter the size of a icon on the desktop, or at least change them all to the same size. Thanks in advance for any ideas.