Open "Anaconda Prompt" and type jupyter notebook --generate-config
You find the file in C:\Users\username.jupyter\jupyter_notebook_config.py
Change the line of #c.NotebookApp.notebook_dir = '' to c.NotebookApp.notebook_dir = 'c:\test\your_root'
Then, go to the shortcut of Jupyter Notebook located in C:\Users\User_name\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Anaconda3 (64-bit)
Do the right click and go to the Properties
In the Target field, remove %USERPROFILE% as stenlytw suggested above.
Then, In the field of Start in, type the same directory of c:\test\your_root\ in jupyter_notebook_config.py
As the simpler way, after step 3, go to C:\Users\User_name\Anaconda3\Scripts
4-2) You can see the file of jupyter-notebook.exe and click it.
5-2) Then, the Jupyter start the folder you specified in jupyter_notebook_config.py. So make the shortcut of this file.