Why am I only see pictures when I connect my Galaxy S7 to my computer?

When you connect your Marshmallow-powered Galaxy S7 Edge to your computer (WIndows or Mac) using the USB data cable, you’ll have the following options that tell the Android what you want to do.

1. Transferring media files.
2. Transferring images.
3. Connecting MIDI devices.
3. Charging.

You just need to open the notification panel from the top of your screen, tap USB for file transfer, and pick an option.

If you only see pictures, you must have chosen the Transferring images option which lets you copy photos and videos from your phone to your computer. Simply change the option Transferring media files to see all your files on your phone.