The chat window is what your visitors see: a button at the bottom right of the page that opens the chat. The Chat window tab of the admin has the six settings that make it yours.
At the top of the chat window, and the tooltip of the chat button.
Shown next to the icon of the button that opens the chat, for example Ask us. Empty: the icon only. On screens up to 480 pixels wide, phones included, the button shows the icon only.
The first message in the chat, shown before the visitor writes anything and again after New chat. Line breaks are kept, and Markdown works: **bold** and links written as [text](https://your-site/page).
The grey text in the empty message box, followed by (type / for commands), on one line: a longer text is cut at the edge of the box. When a conversation has used all its questions, it is replaced by a note to start a new chat.
Your logo on the chat button, in place of the chat icon, and in the header of the chat window. Tick Remove the logo and save to go back to the icon. The file is checked to be a real image before it is kept, in your data folder.
The colour of the chat button, the header of the window and the links in the answers (a source pill takes it when the mouse is over it), written as a hex code like #c05520. Pick one your white text reads well on: the button and the header carry white text and icons.
Write the title, the button text, the greeting and the placeholder in your site’s language: they are shown exactly as you write them. A change reaches visitors on their next page view.
Everything you can change is on the Chat window tab; there is no theme file to edit. What your visitors get with it, the window, typing, ratings and the conversation kept in the browser, is on What your visitors get.
The hosted chat has the same six settings, on the Chat window tab of its Control Panel: Chat window: look and words.