[bug?] If you highlight something in post A and click reply on post B, the highlighted text in post A will be used as quote instead of post B. Seems unintuitive to me. Is this intentionally?
It's intentional. You should have got a personal message when you signed up that tells you a LOT of detail about this.
If you reply to a post then hit the speech bubble button to get the quote
To give this
Where you get better information.
Thanks for letting us know about this, your issue has been escalated to second level support and you should receive a phone call within 48 hours.