1 - The activity is not configured to play sound
Each activity can be configured to play or not play sound. Make sure that the sound is enabled for the relevant acitivity/activities.
To check if the sound connected to an acitivity is enabled, start by going to Manage > Activity Types
Click on an activity type > then click on an activity
The next step is to see if the button saying "Play Sound" is enabled.
If the box is enabled, the acitivity is set to play with sound.
Make sure to see if the other activities has sound enabled as well, as this can vary from activity to activity.
2 - Video is configured to be muted
If the celebration is a video, make sure that the video is not configured to be muted.
To check this, click on your profile picture in the top right corner > My celebrations
You will now be presented with the overview of your celebrations. The next step is to make sure the button saying "Mute celebration popup in browser" is disabled.
If this button is disabled (as shown in the picture above), the celebration should play with sound.
Note: Make sure to check that the YouTube-link containing your celebration is a video that has sound.
3- TV screen is muted or very low
Make sure the TV itself is not muted and the volume is not very low
4 - Hardware (e.g. Chromebox) connected to the TV is muted or very low
The hardware could also be muted. Connect a keyboard and mouse and check if it is muted or the volume is very low.
Note: If you are using Chromebox and it is in "managed" mode, which means it opens the SalesScreen app automatically on restart, turn it off. Make sure you have a keyboard and mouse connected and immediately press Ctrl + Alt + S after you turn it on. Then check the volume of the Chromebox.
5 - MP3 file is corrupted or not supported
If you are using a MP3 file, try to upload a different MP3 file to see if works.
6 - HDMI cable is damaged
Check with a different HDMI cable. The one you are using might be damaged and not transmitting audio.