You know you solved this exact problem in a chat a few weeks ago. Here is how to get back to it.
ChatGPT has a search box in the sidebar that looks through your chat titles and, in many cases, the text inside them. Try two or three distinct words you remember from the conversation, not a full sentence. It is quick, and it works well when the chat is recent and titled sensibly.
In settings, under data controls, you can export your account data. It arrives as a file by email, usually containing every conversation. It is thorough, but it is a big file that is awkward to search by meaning, and it is a snapshot. The next chat you have is not in it.
The problem with the first two is that the chats stay inside one product and you only find them by remembering the right word. A saved archive on your own device fixes both. Every time you finish a conversation worth keeping, you save it once. Later you search across all of them in one place, including chats from other assistants and the web pages you read around the same time.
Stash does this with one click from a small pill on the chat. Search runs on your device, so nothing you saved is uploaded anywhere to be indexed.
Keep every AI chat in one private place. Stash saves your ChatGPT, Claude and Gemini conversations and the pages you read to a searchable memory that lives only on your device. Free, no account.
Add to Chrome, freeMore guides: How to save your ChatGPT, Claude and Gemini chats · AI memory on your device vs in the cloud · How to continue an AI chat in a new thread