facebook chat question pleasE!!!?

[A Guy]

Okay can someone please explain to me what happens? I go on facebook and see a list of people that are in the little chat window, for some people that are on their computers it says WEB with a green dot. For one person specifically, (that's why i'm asking the question) it says they were on their phone online 5h ago, but when I look at the newsfeed, it shows that that person liked a picture 20mins ago, and even changed their profile picture 30 mins ago. WHy does it say 5h? Did they block my chat? I click on her name and the chatting window opens up, so it looks like that person didn't do it. Also, i thought if you turn off chat for someone or at least when I turned off chat for a person, their name disappeared from the list. So how do i know what's going on?
Turn off chat for me or turn off chat for everyone? This hasn't happened before. One day I see this persons been away for 5 hrs when it shows that she changed her profile 20 mins ago. Seems sketchy.

I have the phone number and everything and this is not about whats practical and whats not.