Starting from Android 6.0, there have been some changes on how and where downloaded apps and their data can be stored.
This is the internal storage which contains the Android system, preinstalled apps, email, text messages, and cached data from the apps. You can also install apps that you've downloaded and capture photos, videos, and screenshots to this storage.
Use your storage card as a removable storage to store and access your media and other files on HTC Desire 650 dual sim or any Android phone, or set it up as an extension of the internal storage.
See Setting up your storage card as internal storage.