WPML Translation Management provides you with Classic and Advanced Translation Editors. Both of these editors help you translate your content more quickly and easily.
If you prefer to use the Classic Translation Editor, you can change translation editors by going to WPML →Settings and scrolling down to the Translation Editor section.
Translation Editor options on the WPML Settings page
There are two options:
New translations refer the content you translate from the moment you select this option.
The second option is about content translated previously using the Classic Translation Editor.
For content already translated using the Classic Translation Editor, you should keep using that editor. Switching to using the Advanced Translation Editor usually means you would need to translate that content all over again.
Similarly, you cannot use the Advanced Translation Editor to edit translations done by a Translation Service. You can only edit those translations using the Classic Translation Editor.