alright.... To truely control your auto tranny, you'll end up using these buttons a lot to shift it better.
4 speed tranny, overdrive is 4th gear, if you turn it off, it will ride in 3rd. ECT is a bit more involved than that though, if you're on economy, you'll only downshift one gear when you floor it, with it in power mode, you'll downshift two gears, and also hold the gears a lot better, it's like having a shift kit
You can also control it manually, but that is generally not accepted as a good idea as it increases pressure and heat in the tranny...