Retina display + External HD monitor ( window Icon size cannot be changed)

Dear all,
Our staff uses a 13" i5 MacBook Pro with Monterey 12.0.1/Parallels 18/Windows 10 pro. Also, they are using one external LG monitor.
There is something wrong with the window Desktop icon size - too small.
I have tried the below advance for further steps, but, it doesn't work.
Can anybody help?

Windows virtual machine display resolution issues on Macs with Retina display
https://kb.parallels.com/114700

Retina display + External HD monitor resolution wrong using all options
https://forum.parallels.com/threads...or-resolution-wrong-using-all-options.343736/

 

Use the option external monitor into the video configuration.