Username isn't what it used to be

[user-removed]

So I have just created my account using my gmail and I added my username. But when I logged in the website of spotify, my username is not the same name I have added. It's somewhat a code. What has happened here? How can I change this back? I will have to copy that very long username everytime I will log onto the app. But my name in the app is the same username I've used in my registration. The only problem is the username for logging in. I hope I can fix this immediately.