@grammargirl If you ask it to speak British, ChatGPT3.5 keeps writing American spelling regardless. If you ask Chat GPT 4, it will use "colour" and suggest putting beans on toast. If you don't tell it you're British and want to hear British English, it will suggest 20 things to put on toast, but not beans.
The bot has no idea where you are. Bard has a feature to tell the bot where you are tho, but I didn't do any experiments with it.