Steering Wheel Controls

I think that I have a faulty back button. It does nothing when I push it.
The button below there takes the screen back to the miles to empty.

 

The back button doesn't always do something. When you get a warning such as low fuel, then it will allow you to clear the warning.

 

For the return button to work the center display has to show the return arrow in the upper right corner, see the photo below next to "Units". If no arrow is displayed the button does nothing.

The larger rectangular button below is a custom button that you can assign whatever function you find useful, Toyota calls it "Top Screen", pushing it goes directly to your assigned screen, yours is set to miles to empty.
(Mine is set to tire pressure.)

Your manual starting about page 93 explains everything.

 

That's much clearer now. Thanks!