Hi BAOBINH! HDMI eARC is available on HDMI port 3 and allows for surround sound formats, including premium ones like Dolby Atmos and DTS: X, to pass uncompressed to a device that supports it. So that we can further troubleshoot the issues you may be having, please reach out to Samsung Audio Support at:
• Phone: 1-800-SAMSUNG / Available 8 AM - 9 PM EST, Mon - Fri
• LiveChat or Email: https://www.samsung.com/us/support/#contact_us_for_support
We look forward to hearing from you. ^Tim