Hi,
You can try these steps to your device, on Android tap the app drawer icon from the home screen. Then from the displayed list, tap on the my files icon. Then on the top right corner, tap the icon with four horizontal lines. Tap the Settings option. Select directories on the left, tap the Set home directory option. Then tap to select the desired folder or the entire external SD card where you want the files to be downloaded by default. Then tap the done button. Let me know if this step worked for you. Thanks!