By turning on the "Automatically upload files when connected to Wi-Fi" setting, you can reduce mobile data usage.
This setting is "OFF" by default when you start using the app. If you wish to upload files only when connected to Wi-Fi, please switch it "ON" using the following steps.
How to change file upload settings
Tap Menu at the bottom right of the app.
Tap "Settings & Payment Information".
Open "Device Management".
In the "Automatically upload files when connected to Wi-Fi" section, slide the button to switch it "ON" or "OFF".