In the giosg console, click Settings -> Chat windows to create new chat windows and edit existing ones.
You can edit the texts and position, as well as add your logo to the chat window. If needed you can make changes in the design of the window, by clicking "Open style editor". Here you can edit the css and, if required, override HTML templates.
The chat window that is used in a domain is determined from Settings -> Rooms -> Choose domain -> Chat window (in the Chat settings section)