If I'm understanding what you're asking (newbie here lol), that is how it is supposed to be.
When you click on the link in the postbit, it changes your scheme, but in your profile it still says you're using your old style.
If you logout or clear your cookies, you go back the style you were originally using.
So I don't think that is the error.
If you want to post or attach your showthread, maybe a fresh pair of eyes will see what's wrong with it