That's why I said "in VSCode" because I have no idea what this guy is running, but it's almost a certainty the problem isn't copilot but it's a bad LLM and/or his bad prompt.
The Copilot integrated with Microsoft 365 doesn’t have a model switcher it just is what it is. You are talking about a completely different product that Microsoft calls the same names.
imo, any VSCode user needs both extensions: "GitHub Copilot" for inline completions, and "GitHub Copilot Chat" for interactive, multi-turn coding chat/agent.