I don’t even know why anyone would use Command Promt (cmd.exe) anymore as the default commandline Shell on the Win+X menu: However in Windows 8.1 the default commandline shell when you right-click in the bottom left corner, or hit Win+X, is just that..

But there is a easy fix: Right-click on the taskbar and select Properties in the context menu, then select the Navigation tab. Select to replace Command Prompt with PowerShell. Save and enjoy!