Hello @Sallyaw,
On the right side of the Chromecast Voice Remote you can press the volume buttons to adjust the volume. If this doesn't work, using the remote that goes with your TV and try adjusting the volume and checking to make sure the TV is not on mute.
If the TV remote is able to fix the issue, you can then configure the Chromecast Voice Remote to control your TVs volume by configuring it in the settings by following the steps on this page.
Let us know if you have further questions.
Brett
