The latest version of Jupyter Lab is used when you create a new notebook. You can't choose the older version of Jupyter Lab for new notebooks. Your existing notebooks retain the version of Jupyter Lab that was used to create them. However, when you deactivate and reactivate notebooks, the latest version of Jupyter Lab is used.

Support for the older version of Jupyter Lab in notebook sessions ends six months after the upgrade.

For more information, see Data Science and Data Science Blog.