Copying from another topic to here, so it’s together with the rest of the markup information:
Put the quote end tag on its own line.
[quote]
Text[/quote]
gives:
[quote]
Text[/quote]
But
[quote]
Text
[/quote]
gives
On the blue box: You get that if the system thinks you’re writing something very similar to an existing topic (but in my experience it always matches completely unrelated stuff). Just click the X to make it go away.