Can’t get my remote to control tv sound

The concern is not "Xfinity Knowledge Base" help related. Thread moved here to the proper help section for assistance. 

Hello, please reach out via direct message. We will be happy to help you. 

Here's how to send that requested direct message (private message);

Click "Sign In" if necessary.
 
Click the "Direct Message" icon  in the upper right corner or https://forums.xfinity.com/direct-messaging  
 
Click the "New message" (pencil and paper) icon.
 
The "To:" line prompts you to "Type the name of a person". Instead, type "Xfinity Support" there.
 
As you are typing a drop-down list appears. Select "Xfinity Support" from that list.
 
An "Xfinity Support" graphic replaces the "To:" line.
 
Type your message in the text area near the bottom of the window.
 
Press Enter to send it.

[Permission from and credit given to BruceW].