Columns w/ Parallax – Change direction

Dear team,
on my page below I use on the very top a color section with 1/1 box inside. I need to change the parallax effect of this box: Now it disappears to the very top, but it shall longer be visible at scrolling, i.e. it shall move down. But I did not find a way to realize this. Menu does not offer a reverse movement and +/- are only changing the speed.

Would be great to know how this can be realized

thx a lot & best regards Tilman