How to adjust the metronome on casio privia - Casio Privia Keyboard Case

You hold down the function key/button and then use the PIANO keys with the "tempo" shown above them.
In that section of the keyboard, the C# key raises the tempo and the C key lowers it. You can also use the numbered keys in that section to dial up a particular value. Hold function down and strike the numbers you want then release the function key/button

I don't believe there is an adjustment for loudness of the metronome other than the overall loudness of the piano..