One of the big improvements for JupyterLab , which is the more current generation in the evolution of Jupyter, is that it is much easier to control this, see here.
However, for the traditional (classic) notebook interface, it isn’t as easy. This post describes how.
If you are unclear about which interface you are dealing with, you can go here and pick the upper right block to try JupyterLab.
You can install JupyterLab, if you haven’t already.