Hi, Thanks for the reply, but my problem was understanding the documentation. I've more or less worked it out. It seems the key is to select with the centre of the recolor tool, which means zooming in first. It's a shame it's not as easy or versatile as the replace tool in MS Paint, so I'll stick to exporting and importing to there when I need the more powerful tool.
For the love of god will someone tell me how to use this tool. I select the recolor tool, but all it does is paint the primary or secondary colour over everything, depending on left or right mouse buttton. At the moment, I have to open files in MS Paint if I want to replace colours, then save and open again in Paint.net. How can it be so hard.