Since the single-user server is an instance of jupyter notebook, an entire separate multi-process application, there are many aspect of that server can configure, and a lot of ways to express that configuration.
jupyter notebook
At the JupyterHub level, you can set some values on the Spawner. The simplest of these is Spawner.notebook_dir, which lets you set the root directory for a user’s server. This root notebook directory is the highest level directory users will be able to access in the notebook dashboard. In this example, the root notebook directory is set to ~/notebooks, where ~ is expanded to the user’s home directory.
Spawner.notebook_dir
~/notebooks
~
c.Spawner.notebook_dir = '~/notebooks'
You can also specify extra command-line arguments to the notebook server with:
c.Spawner.args = ['--debug', '--profile=PHYS131']
This could be used to set the users default page for the single user server:
c.Spawner.args = ['--NotebookApp.default_url=/notebooks/Welcome.ipynb']
Since the single-user server extends the notebook server application, it still loads configuration from the jupyter_notebook_config.py config file. Each user may have one of these files in $HOME/.jupyter/. Jupyter also supports loading system-wide config files from /etc/jupyter/, which is the place to put configuration that you want to affect all of your users.
jupyter_notebook_config.py
$HOME/.jupyter/
/etc/jupyter/