History
To see every task in your project, choose the History button (the clock) at the top right of your chat area.

History lists your tasks with the newest first. Each entry shows the prompt the task started with and when it was last active. Choose a task to read its conversation. To carry on with the task, send another message.
In a big project, use the search field to find a task.

Choose Done to close History.
Note: If you can't find a prompt, it may have been a message within a task rather than the start of a task.