Known issues with the new plugin Editor - TinyMCE
From Joomla! Documentation
In Joomla! 3.7.0 there's new Editor - TinyMCE version (4.5) with new features.
Now you can configure the editor toolbar by choosing (drag & drop) which buttons and function display.
Now you can configure many editor "set" to be associated with various user access levels.
- Opening the "Editor - TinyMCE" plugin, the first TAB on the left side opens by default and it groups all the settings below (which is not clear). But the first TAB (Set 2) has no effect on the editor settings used by the super user, which is likely to make changes that will not find using the editor. Only the last hidden TAB Set (Set 0) on the right side has effects for the user Super User.
- Be aware. Existing toolbar/TinyMCE settings cannot be fully migrated, they may only be partially adopted in a Joomla version update.
This pertains only to Joomla! version(s): 3.7.0