OpenAI introduces GPT-5.5 Instant and makes it the default model for ChatGPT, replacing the previously used GPT-3.5 Instant. Tech outlets report that the change is immediate for users who rely on ChatGPT’s default setting. Alongside the shift in model, multiple sources describe updates to how the assistant responds. Decrypt says GPT-5.5 Instant provides more concise answers and is designed to “make fewer things up,” suggesting improvements in reliability and consistency compared with the prior default model. Decrypt also states that the model can remember information provided in earlier conversations, referring to continuity from what a user told it previously. TechCrunch, meanwhile, focuses on the operational outcome: GPT-5.5 Instant is positioned as the new default model within ChatGPT. Neither source details the underlying model architecture, performance benchmarks, or rollout timing beyond the default-model replacement. Overall, the reported update centers on a default-model upgrade and associated behavior changes in response style and conversational continuity.