I can set the custom folder icon to permanent by editing the desktop.ini file, with simply erase some part of the icon file address into iconresource=icon ...
> Right-click on your desktop > select View > choose your preferred icon size. File Explorer: > Open File Explorer > click View > choose your preferred icon ...
Right click a folder -> properties -> customize -> Change icon. Then look at the generated desktop.ini so you know what change by hand next time.
Right-click onto the folder you want to change and then choose Properties In the properties window, select the Customize tab. Then click the Change Icon button. In the opened window you can browse for the built-in icons or select your own in the ICO forma