I have a Plone 4.3 site that was a migration from a Plone 2.5 site. It had been working fine, but for some reason the default editor that shows up when editing any page or c
Plone also stores the chosen editor in the user preferences.
Check http://yoursite/@@personal-preferences
There's a small script which migrates all users to tinymce -> http://plone.org/products/tinymce/documentation/how-to/how-to-set-tinymce-as-default-editor-for-current-users/