Is it possible to change the theme of more than one palette at a time? Or does one have to go through them one at a time and edit them? I'm beginning to get a lot of palettes, and changing them could be hard work!
You can set them to the Default, in which case they will use the Default theme as defined in the Keyboard Maestro Palettes Preferences.
Alternatively, you can Copy the theme, and then select the various macro groups you want to change and Paste.