Samsung GALAXY S7 User Manual page 188

Memory Card (SD Card)
Once an optional memory card (not included) has been installed in
your device, the card memory is displayed in the Storage setting.
For more information, see "Install the SIM Card and a Memory Card" on
page 5.
Mount a Memory Card
When you install an optional memory card, it is automatically
mounted (connected to the device) and prepared for use. However,
should you unmount the card without removing it from the device, you
need to mount it before it can be accessed.
1. From a Home screen, tap Apps > Settings.
2. Tap Device maintenance > Storage.
3. Tap More options > Storage settings.
4. Under Portable storage, tap your SD card, and then tap Mount.
Settings 179