Hi Parrot69,
welcome to the forum.
You have observed the colour sliders very well. The terrain, but, is built up with the displacement ... which is the next tab.
The Fractal terrain is just a normal Powerfractal with all its possibilities for displacements and shading. It just has some special predefined settings.
For the terrain you do not need the colours. For shading with a powerfractal you might want to avoid most times the displacements.
What you can try:
Go to the shaders and create a surface layer. Go back to the Fractal terrain node, enable both black and white colour. Now drag a connection from the Fractal terrain's output to the colour function input of that just created surface layer.
Or you use the luminosity function input (do not use the child-input, as it gets the displacement of the terrain, which is the second time).
I just love to combine the displacements of a powerfractal with the luminosity input of a surface layer, by the way
Volker
