How to set the software download location for Sony z3 seems to be only in the mobile phone itself.

Landlord, like my mobile phone, it is done in Settings-System Settings.

You can try. It seems that ordinary mobile phones are set in that place.

If your phone cannot be set, the general settings will be stored in the phone by default.

If you want to store things in the SD card at this time, I suggest you use the computer version of the application treasure to download things.

Before downloading this software, you can set it in Settings-Application Settings in the upper right corner.

After successful setting, when you download the software, it will be automatically stored in the SD card for you.

Moreover, the software and games in the App Store are quite complete, and their compatibility with mobile phones is also good.

You can download it with confidence.

I hope it will be helpful to you and I hope it will be adopted.