I also find these new colors hard on the eyes.
You can change your color scheme by clicking on "User CP' up the top of this page on the left hand side, then click on "Edit Options" on the left side. Go down to the bottom of the page to "Forum Skin" and on the right you will see a pull-down menu that says "Forum Default". Click on the little arrow and you can choose another color scheme from the list. Then click on "Save Changes".
I really like the "California Gold" colors.

I found it works fine on the other forums here but this "Theme Park Attractions and Strategies" forum reverts back to this new blue scheme for some reason (although it does say beside "Forum Skin" that some forums may revert back temporarily).