First, don’t enter any private or confidential information into ChatGPT and similar tools. It’s possible that developers may review your entries to improve the next version of their model.
If you want to make sure your inputs aren't used to improve the model, you can turn off that feature in the settings. Click on your name, then Settings, then Data controls, and turn off the switch called “improve the model for everyone.”
Another option is to use the feature called “temporary chat.” At the top of the page, click on the menu that says “ChatGPT,” and then click the option that says “temporary chat.” Then your chat won’t appear in your history and ChatGPT won’t save anything from your conversation.
You can do the same in other tools. In Perplexity’s settings, the switch is called “AI data retention.” In Google’s Gemini, click a button in the lower left called “activity.” At the top of the page that comes up, you can click the menu that says “turn off.” Claude doesn’t use your inputs for training unless you opt in.