If a user's email has changed and you need to update it in Monolith, the change must be made directly in the Monolith database.
Here are the steps to make that change.
Install MySQL Workbench, open it, and create a connection to your Monolith database.
Open the Monolith database connection in MySQL workbench.
Navigate to your Monolith Database under the "schemas" tab and expand the schema and tables list. The Monolith db is usally called "monolith_db".
Scroll to the "users" table and open the table in Workbench to reveal the user records.
Find the user record that you want to update and click into that user's email column. Then type in the new email.
Click the "apply" button at the bottom right in Workbench, then click apply again in the confirm dialog that appears.
Once this is completed, the user's email has been updated and they can start logging into Monolith with that email address.