Is there a way to increase the output volume ?

Hello,

I use Audials Radio version 9.9.5.0 6g20121164a (downloaded to day from the PlayStore) on a Samsung Galaxy S8 smartphone.

It connects to a NuPrime BTR-HD bluetooth receiver.

Theproblem  I have is that the output volume is too low.

Is there a way to adjust it ?

Thank you,