Okay, so sometimes people's brains can get really messed up and they might start thinking and doing things that are very different from what most people think and do. This is called insanity.
Now, if someone with insanity gets some help and takes medicine or other treatments that make their brain work better, they might start thinking and acting more like other people. This is called getting better or recovering.
But sometimes, even if someone gets help and starts thinking and acting more normally, they might still have some leftover problems from when their brain wasn't working right. This is called settled insanity.
It's kind of like if you have a toy that gets broken and you try to fix it, but even though it's mostly working again, it still has a scratch or a dent or something that reminds you it's not perfect. Even though it still works fine, it's not exactly the same as it was before.
So settled insanity is when someone's brain is mostly feeling better, but there are still some little things that are different and maybe not quite "normal." It doesn't mean they're still really sick or that they're dangerous, it just means their brain is still healing and working out some kinks.