I am using the web-interface of ChatGPT and I always choose GPT-4. I do not change the system command to ChatGPT.
However, I notice that even in different chat sessions, the ChatGPT performs completely different.
For example, in one chat session, I ask ChatGPT to write the outline of an article, and it does that properly.
However, if I create a new chat session, then send the same prompt, it will not produce an outline, instead, it will produce the following:
Thus, to generate the outline, I have to go to the old chat session and send prompt.