You can update all the information associated with an existing user -- profile, role, password, and working hours. Anyone with the role that has Setup Permissions → Team management section enabled should be able to update and make changes to an existing user. Any changes made to the account will be reflected under the logs section of the user profile.
Update the existing user
1. Go to Setup → Team. 
2. Click on the user you want to update.
3. Make the necessary changes you like.
4. Click on the Save button at the top-right corner of the page.
Logs
In the logs tab, you will see all the changes done on that user account from the time it was created. To access the logs, click on a user and go to the logs tab.
Logs Elements
Event - This is the action that took place within the user profile.
Author - The user who made the changes. This will reflect the first and last name that is set up under their user account.
Updated Parameters - This is a clickable section that will show you the information that was updated. Click on the item to see the old and new values.
On password updates, the old and new values will not be shown for security purposes.
Date - The date and time for when the update occurred.