1. From the Wii U Menu, launch System Settings.
2. Using the left analog stick, scroll to the right to find the TV icon and press the A button.
3. Select TV Audio-Output Type near the bottom of this page.
4. Click the middle option, Stereo.
5. Press the B button to return to the main menu and relaunch the game.
If the sound plays correctly now in the game, then you may need to review your television or speaker settings / configuration before trying to enable surround sound again.