This documentation is not using the current rendering mechanism and is probably outdated. The extension maintainer should switch to the new system. Details on how to use the rendering mechanism can be found here.
Configuring content elements can be done for the frontend and for the backend.
The easiest way to change the appearance of content elements in the frontend is by using the "Constant Editor". These settings are global, which means they are not configurable in a single content element. Constants are predefined.
TYPO3 CMS is using TypoScript as a configuration language and is used by the frontend rendering. By overriding TypoScript you can influence the rendering of most of the frontend.
For the backend, fields can be shown or hidden, depending on the fields you are using or the fields an editor is allowed to use. Configuration like this is done using "Page TSconfig" or "User TSconfig".