How can we edit the rivers altitude?

Hi, :wink:
I have continent with ocean, sea, montains etc. The sea level it’s ~990 meters and the maximu sea depth it’s -500meters.
I want to generate some rivers, thy come from the montains, and to that i have to set the high/altidute of the curve points. But it doesn’t works the river stay at the same altitude.

Thank you.