Users can customize icons in Windows 11 by following different methods depending on the type of icon. For folders and shortcuts, right-clicking the item and selecting Properties allows users to change icons easily. Taskbar items require pressing Shift while right-clicking the closed app. Desktop icons like "This PC" and the Recycle Bin can be modified through Settings > Personalization > Themes > Desktop icon settings. More complex changes, such as altering icons for file types or drives, involve editing the Windows registry.
Windows retains a selection of classic icons within DLL files, including moricons.dll, pifmgr.dll, and netshell.dll. Users can also access the Windows Icon Archive project for a repository of icons from various Windows versions, though .png files need conversion to .ico format for use.
Limitations include the inability to change icons for new folders automatically, modifications not reflecting in Quick Access for special folders, and restrictions on altering application icons. Programs like OpenShell can help modify taskbar and Start menu icons, but achieving a perfect replica of older versions is not possible.