As far as I can tell, there is no way to make your SD card the default storage location on the Galaxy S7. However, you can merge your SD card into Adoptable memory and move apps, images, web browsing and media onto the SD card in a piecemeal fashion. It is less than ideal but at least we have an SD card slot now!
One way to integrate your SD card into your onboard storage allocation is with Adoptable storage. Samsung initially said they weren’t going to include it within the S7 even though it is standard in Marshmallow. Fortunately, where there’s a will there’s a way.
1. Back up everything you can’t afford to lose on the phone.
2. Navigate to Settings, About phone and Build number at the bottom. Tap the build number five times to enable debugging.
3. Connect the Galaxy S7 to your PC with a USB cable.
4. Type or paste ‘adb shell’ in a CMD window (Windows OS).
5. Type or paste ‘sm list-disks’ and record the disk IDs that come up.
6. Type or paste ‘sm partition DISK:TYPE:RATIO’.
Enter the disk ID where it says DISK, TYPE is either ‘private’ to adopt the entire microSD card or ‘mixed’ to use a portion of it. RATIO is only used if you select mixed. So a command would be something like: ‘sm partition disk:182:160 private’ to adopt the entire storage. Or ‘sm partition disk:182:160 mixed 50’ to adopt 50% of the microSD card.
7. Allow the process to complete and then verify.
Set apps to save to SD card
Some apps can be moved to the SD on a Galaxy S7 while some cannot. When updated, some apps download back to internal storage so keep an eye on space when you’re using them.
1. Navigate to Settings, then Storage and Internal Storage.
2. Select Apps and the app you want to move.
3. Tap Change under ‘Storage used’ and select SD card.
This option isn’t available on all versions of the S7 as the carriers make their own changes. It also doesn’t work with all apps for some reason so it will be an exercise in trial and error to see how much space you can save.