How do I reverse platform behaviour gravity?

Hi, working on a game that instead of falling down it will be "falling" up, like that there is gravity on top.

I wanted to reverse what the Platform Behavior is doing adding negative numbers but doesn't seem to work.

Is there anyway to achieve this?

Thanks.

Actually if you add negative number to gravity only must work.

savvito123 You are right, I changed all of them and it went crazy, thanks!