Maybe I miss something

In 9.0.48 I can add powershell type command script to do something on windows environment

but I just find I couldn't add new build type for the powershell
Current our environment of [step][build][powershell] inherit from 9.0.48
So I couldn't change step from shell(linux) to powershell(windows) for the same name
I need to copy an exist powershell step for it and give it as almost same name...