Don’t feel ashamed, your brain is programmed to do this. It’s called ‘cognitive ease’ – and because you already agree with something you start to skim read.
Alternatively, when you hit something you disagree with, your brain tells you it’s a threat. So you disengage and skim read.
You can’t win either way. You can just be more aware that the intuitive part of your brain tries to skew things you read to reflect what you already think. That’s because changing your mind takes effort and analysis which are labour intensive – much easier to be in an echo chamber full of allies or label everyone who disagrees with you as a fascist.
Sorry for playing the old switcheroo mid way through, but I hope you see the point of it and can take away something useful. :o)