restoring media volume after tss "warnings/dings"

The system automatically lowers the volume when the GPS talks etc... I have found when the safety warning ding the sound is reduced. The problem is, it doesn't go back up. My best fix is to lower off and on the system. Cycling though the different sources also usually works. Anyone care to state an easier work around to get the volume back up?

Also, connected with this glitch is the silencing of Waze occasionally. The music lowers, but no voice. Toggling the gps volume on off does nothing. Haven't found a solution rather than shutting the whole car off and back on again.