The new WordPress editor from 5.0 just overwrites the Fusion Builder interface.
So if you go and try to edit a page or post, you will see the new horrible WordPress editor called “Gutemberg”.
How to get rid of that and display the old Fusion Builder?
Go to this page and download the plugin called “Classic Editor“.
Install the plugin and activate it.
After that, go to a page or post and try to edit it, you will see the Fusion Builder interface.
No need to update the Avada theme at all, even if it’s a good idea to do it, but first, don’t forget to backup your WordPress website.