Color of the bar chart changes when i change parameter value

Hello everyone,

I have column which is running based on the formula ( if X > Parameter_1 then "sth" else "sth else"). I have colored the bar chart sections green and red. However, when i change the Parameter_1 value the colors of the bar chart sections change to default ones light blue and dark blue. Is there a way that i keep the same color no matter of the parameter changing?

Thanks for answers in advance