How do I set config variables on a Mac?

edit

I am using SageMath Jupyter notebooks with Mac OS 11.2.2. I wrote:

import pickle
rfile = open('/Users/barrybrent/test31jan21no22.txt','r')
rs = pickle.load(rfile)
rfile.close()
s = stripQuotationMarks(rs)
print(s)
print(len(s))
for k in [0 .. 3]:
    print("")
    print(s[k][1])

Jupyter answered:

IOPub data rate exceeded.
The notebook server will temporarily stop sending output
to the client in order to avoid crashing it.
To change this limit, set the config variable
`--NotebookApp.iopub_data_rate_limit`.

Current values:
NotebookApp.iopub_data_rate_limit=1000000.0 (bytes/sec)
NotebookApp.rate_limit_window=3.0 (secs)

I'm a Terminal amateur, but I tried various suggestions on the web involving language with the word Jupyter in it, and Terminal answers with variations on 'zsh: no such file or directory'.

Any other suggestions?