Use Google translate to read my reply. That's what I did to read your issue...but in the future, try to post in English as more people will read and answer it. No disrespect to you or your language, it's just more common to use English as the middle of the road for everyone.
Go into the RetroPie Menu for audio by using the actual Retropie Menu, not the emulation station shortcut. Once you're in the RetroPie Menu, look for the audio options and switch the output from HDMI to 3.5" Audio jack.
The menu is easy to navigate, you'll see it.
The board is just an amplifier, but to make sure your audio output is set right/working, use a set of headphones to test it. If you hear sound, you know the issue is your amplifier.
Hope that helps.