Playing around with settings in Android Auto. Cannot figure out how to customize the icons shown on the left of the screen (circled in red). I'd like to place my text messaging there and have it show on the split screen. Currently, the split screen shows map and XM radio apps (like to remove the XM apps).

 

You can not customize shortcuts on the left menu in Android Auto or CarPlay. They appear based on last used app.

I can't see the circled area in your picture, but I am assuming you mean the AA menu on the left.