Updating the JCE Content Editor
The JCE Content Editor is a little bit different from other 3rd party extensions.
You will be notified of the availability of a JCE Component or JCE Plugin update via the Extensions: Update screen.
But not of the availability of a commercial JCE Addon (Example: Image Manager Extended).
Commercial Addons are instead listed in JCE's own Extension Updater screen as they become available.
How to update JCE Content Editor Addons
Select Components > JCE Content Editor from the top menu of your website's Control Panel.
Then select the Updates button - see image below.
Perform a FULL backup of your website (database & files) before you update Joomla! extensions.
Extension updates can potentially break your website.