Adding custom field to new threads?

[Bad Bunny]

What they are sarcastically trying to tell you is that you posted your question in the wrong forum.

But to help you, there are a couple ways to go about this, but I am not entirely sure of what you need. Do you want this field to be different every single time they post? Like a "now listening to" field? Or do you want it to stay the same for each post, like a "real name" field that would show up in their posts?