Create a course. Enrol two users as students. Create a chat activity. Log in as each user and enter the chat and type some messages (both users have to be in the chat at the same time in order for a chat session to be created, so use different browsers or private window). Log in as the admin. Search for the setting ‘fullnamedisplay’. Change it to 'firstname'. Visit the course. Click on the chat activity. Click on ‘View past chat sessions’. Confirm you can see the full names. Log in as one of the students. Visit the course. Click on the chat activity. Click on ‘View past chat sessions’. Confirm you can only see the first name.