Locating Window soften edges

I’m drawing through a tutorial on line and he wants me to pick “Locating windows soften edges”. It don’t show up on my drop down when I pick windows. Do I need to turn something on or what?

Thanks

window/default tray/soften edges (version 2017).

It was probably an old tutorial you were seeing as the various trays were listed directly under “windows” previously. Now they are listed under “trays”.