Changing your default email address in Canvas will not affect the address that is used to log into Canvas. This holds true for both Degree Program/Residential Canvas (canvas.harvard.edu), and for Professional Education Canvas (exed.canvas.harvard.edu).
After changing your default email address:
For Residential Canvas users, use the email address that is associated with your HarvardKey to log in. If you are logging in with HUID and have not yet claimed your HarvardKey, please visit key.harvard.edu.
For Professional Ed Canvas users, use your original email address that you have used to log in.