Here’s what you need to do to change in Viber:
1. Log in to the application menu
After opening Viber, click the button with three horizontal lines in the lower right corner of the screen. From the menu you can select the Settings tab and consistently Notifications.
2. Change the settings
The next step is to scroll down where you will see the option Use System Sounds, which is disabled by default in Viber. To turn it you must tick the box that is located next to it.
3. Select the ringtone you want to ring Viber
Open the Call Ringtone, which will open additional menu, which will see Reinstalling ringtones to your device. Once you do you can repeat the same steps and Notification Sound, which is located just below the Call Ringtone menu Notifications.