Hi,
I always seem to suffer from a misusage of the forum: How the hell do I make a quote of a previous post, so my answer also appears under the original post under that answer-popdown, plus, how the hell do I make a quote so the original poster in added on the right onto my post?
Could you provide me with a simple step-by-step? Thanks!
The easiest way to quote is to highlight the text you want to quote and click the Quote button that pops up. This automatically inserts the proper code block and marks your post as a reply.
If you want to quote the entire post, it’s better forum etiquette to just click the Reply button on their post. This will show an indication on your post that you’re replying to theirs directly, and viewers can easily click it to view the original post (and vice versa). The only time this doesn’t show is when your reply is immediately after the post you’re replying to (such as my reply). The person you’re replying to will be notified in either case.
Edit: I’ve edited this post a few times because I was experimenting and had some slight misconceptions along the way. At first I thought that using the highlight+quote method did not mark one’s comment as a reply (with the mutual linkage), but it looks like it does, except in the case where your reply is immediately after the target post/comment. In any case, clicking Reply at any time on anyone’s post/comment will change the target of your existing reply and not wipe out your text which is handy.
If you are on PC, select the text with mouse, then there is a ligth grey popup menu that appears, click on it, here you are!
You can also copy the URL of a specific post in a thread in your browser and paste it in you own post to have a preview of a complete post (also works between different threads) like I do here with @vegeta897’s post. Thank you @vegeta897!
Nice! Very kind of you, thanks for those infos.
A test 
Ok makes sense that the OP does not appear, if I quoted the very last post before mine… I just find that confusing.
You’re not wrong to think so, since it’s one of those features that silently break expected behavior for the sake of a cleaner looking thread.
Another test
Quick test:
Can you highlight select and quote this line?
Can you highlight select and quote this line?
Can you highlight select and quote this line?
LOL, no I can’t quote the two below lines, it seems.
But you did. The “helpful” forum software collapsed it, though.
See the arrow on the top right of the quoted text… 
Edit: caret, not arrow
They quoted the first line only. If they had quoted more than one line, they would be included. It only collapses the rest of the post which wasn’t quoted.
The problem that @4tey was illustrating is that there’s a bug with being able to quote lines that contain formatting. Apparently this is a hard-to-reproduce bug that not everyone is experiencing.