Can’t stop ChatGPT from forcing GPT‑5 even with scripts

Understanding and Managing ChatGPT Model Preferences: An In-Depth Overview

In recent experiences with ChatGPT, users have encountered challenges when attempting to control the AI model version—specifically, trying to enforce the use of GPT-4o instead of being defaulted or switched to GPT-5. This article aims to clarify the underlying mechanisms related to ChatGPT’s model preference management, explore why certain attempts to override defaults may fail or cause issues, and suggest best practices for users seeking greater control over their interactions.

The Role of Cookies in Model Preference Persistence

ChatGPT employs browser cookies to remember user preferences, including the choice of AI model for new and ongoing chats. Two key cookies are involved:

• oai-model-sticky-for-new-chats: A boolean-like setting indicating whether the user’s model preference should persist across new chat sessions. Defaults are often set to false.
• oai-last-model-config: Stores the currently selected model configuration, such as GPT-4o or GPT-5.

These cookies enable ChatGPT to maintain consistency in user experience unless intentionally changed.

Challenges with Manual Cookie Manipulation

Some users attempt to manually modify these cookies—using scripts and browser extensions like Tampermonkey—to enforce a specific model setting. For example, setting oai-last-model-config to GPT-4o to prevent auto-switching to GPT-5. However, there are notable issues:

1. Site Crashes or Malfunctions: Directly overwriting cookies can cause the website to crash or behave unpredictably.
2. Automatic Overrides: ChatGPT’s internal logic often overrides manual cookie changes, resetting the preferences based on server-side configurations or internal scripts.
3. Multiple Cookie States: Simultaneously existing cookies with conflicting values (e.g., true and false) can lead to inconsistent behavior or reloads.
4. Persistence of Defaults: Deleting or modifying cookies may temporarily help but often results in the settings reverting upon page reload, or the site reinitializing with default preferences.

Why Does ChatGPT Manage Cookies This Way?

The cookie-based approach allows server-side and client-side control over user preferences. It also indicates potential measures to ensure users are guided toward newer, promoted models like GPT-5, which might be a strategic or product decision. The presence of these cookies and their overrides can sometimes be seen as measures to subtly influence user model selection, creating a “dark pattern” perception