Can someone enlighten me where to find the Fare Rules on AA flights?

I remember there used to be a very tiny button on the vary last screen before purchase / hold, that you can click and it brings up a pop up window for the full details of the fare rules, in particular, whether it requires a fee to change or a cancellation fee to receive residual value of the ticket should it be canceled.

I could not find anywhere on AA booking process that I can find such information - all I see now is either a Lowest or a Flexible - then there is a Flexible and a Fully Flexible fares.

Just how people can find out the fare rules of the AA ticket prices?