Old models are gone (almost). Here is how to get back some.

First things first, here are screens to enable the 4o model back: Step 1: Head to Settings:

Step 2: Toggle “Show Legacy Models”

And Now… GPT5:

0) TL;DR Quickstart

• Pick the right brain: Use GPT‑5 for most work. When stakes are high, switch to GPT‑5 Thinking (or Thinking Pro if available). Ask it to take its time.
• Set the goal, guardrails, and deliverables up front: objective, audience, tone, format, deadline, constraints.
• Ask it to propose a plan before it executes. Approve, tighten, then go.
• Force quality loops: “Give 3 options → score with a rubric → improve the winner → show a changelog.”
• Upload your materials (files, data), then say: “Integrate only what’s relevant; cite sources; mark assumptions.”
• Iterate like a manager: Review, comment, and ask it to revise. Don’t re‑prompt from scratch.

1) Setup That Pays Off

Model & depth

• Default to GPT‑5.
• For hard tasks (novel code, tricky analysis, creative strategy), switch to GPT‑5 Thinking.
• In the first message, set a depth budget: “Spend up to 60 seconds planning; target 10–15 key reasoning steps.”

Personalization