I have come recently from R to Positron and trying to customize it, I would like to change some settings on Themes colors and fonts, and change them, but on going out I get a message saying that I can't change the setting and that my changes will be not kept. And so it is. I ask: what must I do in order to keep my changes? Or, since my version is Desktop and not Pro, this option is not for me? Thank you.
You should be able to save your settings! Could you tell us which version of Positron you're using? (Copy from Help -> About), and paste the exact error message you are seeing?
This usually happens when the settings.json file Positron uses has errors in it or is in a folder that isn't writeable. You can inspect this file with the "Open User Settings (JSON)" command in the Command Palette.
Let us know what you find!