Modern UI 2 ICONs

The MultiLanguage.nsi example includes MUI2.nsh which eventually includes Interface.nsh.
I wanted to use the language options so I started down that path. When I got to changing the Icon I noticed that the typical "Icon" command did not work. After some attempt to find it in documentation I ultimately just searched NSIS files and found where the install and uninstall icons were defined. To change my icon I used the same commands right after the include statement which appeared to work.
;--------------------------------
;Include Modern UI
!include "MUI2.nsh"
;Overrides to Modern UI
!insertmacro MUI_DEFAULT MUI_ICON "D:\NSIS\Projects\ConfigPC\Nokia.ico"
!insertmacro MUI_DEFAULT MUI_UNICON "D:\NSIS\Projects\ConfigPC\Nokia.ico"
;--------------------------------
However, here is my problem which is not completely unique to the Modern UI 2 case. The file icon, as well as all subsequent page icons, have changed as expected. It is the Windows File Manager lower display application icon that has not changed. Example attached.
Where is this defined and how would I change it?

Please read the MUI docs, you don't need the macro to override, just define MUI_ICON. The wrong icon is just a Explorer caching bug, rename the .exe and you will see the correct icon.

"MUI docs"? What am I missing?
I searched NSIS help and "MUI_ICON" returns "No topics found".
Is this it?

Yes

Did not find what I needed there but searching examples I was able to simplify my code so it works. The cached icon did get resolved on its own but it was confusing.

Click [Expand All] on the top before searching for MUI_ICON and then you should be able to see it.