In order to stop Gemini from training on your personal conversations, you’ll need to turn off the ‘Gemini Apps Activity’ option by going to the settings page on the website or iOS/Android app. Google is soon going to change the name of this setting to “Keep activity” after a new update, but the process to turn it off will remain the same.

Gemini is also getting a ChatGPT-style Temporary Chat window. Conversations made here won't influence future chats or show up in recent history.