Sygic GPS Voice Navigation Volume Issue
If you are using
Sygic Navigation and the voice instructions are very quiet.
If Sygic itself has no way to increase the volume of the voices and the adjustment under factory settings/volume/nav show no effect.
Down ground the Sygic Navigation App to version 18.xx and you will be able to set the navigation order as per the below setting which currently is no available with version
20.xx

For Sygic version 22.0.2
Go to Settings - Language and Sounds - Voice - Tick one of the voices - now you should hear your chosen voice and see the tick on the right side.