Hi Dave!
The volume of the HW-A450 can be controlled by a Samsung TV with the Samsung One Remote, and select other models and manufacturers.
To learn more about this feature and how to enable it on the HW-A450, reference page 23 of the user manual: https://downloadcenter.samsung.com/content/UM/202104/20210414174628224/HW-A450_ZA_FULL_00_ENG_210112.0.pdf
For further assistance, please contact Samsung Customer Support at 1-800-SAMSUNG / Available 8AM – 12AM EST 7 days a week.
^Tim