I have the exact same problem and have done everything you told the person at
https://itch.io/t/35848/100-colours-is-extremely-d...
to do, but you mention to right click the image before painting, and go to manage palette, but that is not there. This is a picture of wht happens when i right click the image BEFORE painting, as you say.
I am unsure of what to do, can you help me avenge Harambe in fabulous painting?
I Have the Pro version, I bought it, downloaded the zip, installed it, did not even touch the non-pro version, so that's not installed. I made sure and activated my key, and did not mess with any of the settings, but I looked through them all. (90% sure)
I checked the FAQ and saw this: A: Yes, when using PRO and 100 colors the background makes a big difference. How Rustangelo works is it uses different opacities to get the correct color. By having a darker background color, your colors will come out different in the painting than using a lighter one.
I used the white background like it told me to in the tutorial. If that isn't the problem and it does have something to do with Palette manager, I'm still confused as to where to find it.