Why do most of the people gets suddenly interested in me when I post pics or videos online, writing stuffs I can't say here, but totally ignore me the rest of the time when I am a normal human being in search of social interactions?

This guy added me from fa since I left my discord username public. He liked my draws and at first he seemed nice and friendly, but then he started acting strange. This was the last interaction we had. I'm thinking to post more of these stuffs, because I get a lot of these kind of people in my DMs!

Why do I need to download the YouTube app to put customized covers on shorts? Why cant I do it on the website like everything else???