Board Thread:Support Requests - Getting Started/@comment-32210970-20170821145711/@comment-168424-20170822010950

There is no way to change a gallery to a Slideshow/Slider in Visual Editor without switching to Source Editor.

Fandom's Help pages stink, but Help:VisualEditor is really where you need to look for Visual Editor features and it doesn't mention Slideshow/Slider.

That is all.