Board Thread:Wiki discussion/@comment-35030550-20180407195135/@comment-26397550-20180407211130

The visual editor is damaging, broken and incompatible for editing for most pages. It's not something that can be enabled or disabled necessarily when the cases of it being disabled are not in our control.

It's best to learn how to use the source editor ASAP as it doesn't break pages like the visual editor does. You can still check what your changes look like, and you can have a lot more to change without much issue.