try reordering commands

Dockerfile

@@ -23,12 +23,13 @@ RUN pip install --no-cache-dir --upgrade pip && \
 COPY notebooks/ notebooks/
 COPY data/ data/
 
-# Make sure 'jovyan' user owns these files/folders
-RUN chown -R jovyan:users /home/jovyan/work
 
 # Switch back to 'jovyan' user (the default in the jupyter/docker-stacks images)
 USER $NB_UID
 
+# Make sure 'jovyan' user owns these files/folders
+RUN chown -R jovyan:users /home/jovyan/work
+
 # Expose Jupyter's default port
 EXPOSE 8888