What does it mean when this happens?

[Josh]

I did a test on Facebook that I selected a random person (someone I always Speak to) on Facebook chat on my computer. After I refreshed Facebook by loging in again, this person came up as number one on my chat when he was offline and in my favourites on mobile Facebook.

I then tried this with my crush and my old crush, both came up as number one friends when they were offline on Facebook chat on my computer. I reset my mobile Facebook and they both came up as my favourites. I left it as it was and didn't select them on Facebook chat on my computer. Soon they both dropped out of my favourites on Facebook mobile and as number one friends of Facebook chat. I didn't select them on Facebook chat and suddenly they again appeared as number one on chat on my computer when they went offline. I refreshed my mobile app and they appeared on my favourites. I have seen my current crushes profile a few times but not much. I haven't seen my old crushes profile at all.

A girl sent me a message randomly and after she sent the message she was online and appeared as first on my computer in chat. When she logged out she was still number one. I again refreshed my mobile app and she appeared on my favourites.

What could this mean?
But how about the people I haven't spoken to and they appear as number one in chat anyway.

[skwind]

They were the last person(s) you talked to. Facebook assumes that when you talk to someone you will do it again and moves them to "number one" or into your favorites for easy access when you go to talk to them again