If you have an AppRadio Mode compatible app you use more often than the others, you can set this app to start up when you click 'Apps' on your head unit. Here is the correct way to set this up (with screenshots)...
This should work with any AppRadio Mode capable Pioneer head unit and a compatible iPhone.
How to set up Launch Through in AppRadio Mode
1. Download and install the latest version of the AppRadio app from the App Store. The latest version is 2.8.4 which was released yesterday.
2. Launch the AppRadio app on your iPhone (do not connect to your head unit just yet).
3. The following pop-up message should show up:
New feature: Do you have a favorite compatible app? You can set it to launch automatically in Settings/Help (Launch Through).
Clicking 'OK' should take you to the Launch Through setting.
4. If the above pop-up doesn't appear, click on the Settings/Help button in the AppRadio app.
5. Click on Launch Through. It should be the first option under Settings.
6. Turn on Launch Through.
7. Turning on Launch Through should bring up a list of the AppRadio Mode compatible apps you have installed on your iPhone. Pick any app you want from the list. Doing so will put a check mark next to the app you pick.
8. Done! Connect your iPhone to your head unit and click on 'Apps'. Now, instead of showing the AppRadio Mode homescreen, the app you picked in Launch Through should launch. You can change your pick at any time by going through these steps again.