You can't really change the IDE, but you can change the script editor...
Go into a script, doesn't matter which one, and go to the design menu, options. Choose the editor font tab and switch the foreground and background colours..
Then in the coloring tab, ensure all the backgrounds are set to window background and set the foreground coluors to what you want. If you want to use a color that's not shown, you can add a custom colour on the Design menu, custom colours option. .I like to use Orange for PowerScript keywords, so in the dialog that opens, just select orange and press add to custom colours.. it will then be available on the Coloring screen.
So then in the coloring screen, I can set the colour for keywords..
Also, I like my string literals to be bright green, so set it like this..
I've been doing this for a many many years.. always hated the large expanses of white screen.
HTH - Adrian