Not sure about where the website setting is, but there is also a setting in the chat scripts that you can use. Here are the instructions:
Play your game in studio and then copy the ClientChatModules folder from Chat. Stop playing and paste this back under Chat. Remove everything from this folder but the ChatSettings module.
This settings module has a good amount of ways to customize both the look and functionality of the chat. The setting you are interested in is:
--- Replace with true/false to force the chat type. Otherwise this will default to the setting on the website.
module.BubbleChatEnabled = PlayersService.BubbleChat
module.ClassicChatEnabled = PlayersService.ClassicChat
You can simply change the BubbleChatEnabled setting to true.