The chat module has two themes: Compact and Bubble.
When a chat is created the default theme is Compact.
Is there a way to change the default theme to Bubble?
I'm also looking for the answer to this question - Thanks!
Until a front-end control is added for teachers:
(1) Either you can create an independent link to the chat that adds &theme=bubble to the end of the URL
(2) For the case that you or your site admin are able to modify core files:
Here is a back-end mod that will affect all AJAX chats across your course/site: