Open the notebook in Jupyter Notebooks and look in the upper right corner of the screen.
It should say, for example, "Python [env_name]" if the language is Python and it's using an environment called env_name.
Activate a conda environment in your terminal using source activate <environment name>
before you run jupyter notebook
. This sets the default environment for Jupyter Notebooks. Otherwise, the [Root] environment is the default.
You can also create new environments from within Jupyter Notebook (home screen, Conda tab, and then click the plus sign).
And you can create a notebook in any environment you want. Select the "Files" tab on the home screen and click the "New" dropdown menu, and in that menu select a Python environment from the list.