HTTP User/Pass Grab Confusion

First and foremost, my knowledge of this subject is limited. So i'm reaching out to learn more information..Any support would be greatly appreciated.

I've been trying to use wireshark to learn more about different network traffic, how protocols work, etc. Specifically, i've been trying to see how it's possible to sniff a user/pass off my friend's website (don't worry, he made it soley to help me and there are no inappropriate intentions). He made a basic HTTP website to ensure the minimum security. When i log in, on my computer, using my own username and pass, i can see that wireshark captures my information and i'm able to see my own username and pass.

However, if i use my phone to log in (w/ my own information), or if he logs in from his own computer, those username and passwords don't show up. Nothing shows up. I'm confused because we both expected that information to appear on wireshark like it did when i signed in from my computer.

As i mentioned above, my knowledge isnt deep with this topic, so any point of direction would be helpful!