This is a really dumb question, but how do I change my pfp on here?
Your profile pic is imported from your Xbox Live profile. Change it via your Xbox or the Xbox app, or the Xbox proile on the Xbox website and it’ll be reflected here.
To add to the above, often there is a delay with the picture changing here after you have selected a new one. Don’t be concerned if that happens. Just give it a bit of time to update.