Jupyter notebook sys.path 変更

Question

Jupyter notebookのsys.pathをpython2.7からpython3.7へ変更したい

現在のsys.pathは

['',
 '/usr/local/Cellar/python@2/2.7.15_1/Frameworks/Python.framework/Versions/2.7/lib/python27.zip',
 '/usr/local/Cellar/python@2/2.7.15_1/Frameworks/Python.framework/Versions/2.7/lib/python2.7',
 '/usr/local/Cellar/python@2/2.7.15_1/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-darwin',
 '/usr/local/Cellar/python@2/2.7.15_1/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac',
 '/usr/local/Cellar/python@2/2.7.15_1/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac/lib-scriptpackages',
 '/usr/local/Cellar/python@2/2.7.15_1/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk',
 '/usr/local/Cellar/python@2/2.7.15_1/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-old',
 '/usr/local/Cellar/python@2/2.7.15_1/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload',
 '/usr/local/lib/python2.7/site-packages',
 '/usr/local/lib/python2.7/site-packages/virtualenv-16.0.0-py2.7.egg',
 '/usr/local/Cellar/numpy/1.15.0/libexec/nose/lib/python2.7/site-packages',
 '/usr/local/lib/python2.7/site-packages/IPython/extensions',
 '/Users/ryuta-sh/.ipython']

を '/usr/local/lib/python3.7/site-packages',へと変更したいのですが方法がわかりません。教えてください！

試したこと

sys.append('/usr/local/lib/python3.7/site-packages/')
を冒頭に挿入する　→　動く

jupyter notebook での新規作成でpython3をちゃんと選んでいます。

補足情報（FW/ツールのバージョンなど）

jupyter 1.0.0
pip 19.1.1 /usr/local/lib/python2.7/site-packages/pip (python 2.7)
pip3 18.1 from /usr/local/lib/python3.7/site-packages/pip (python 3.7)