How to change your username on Twitter

To Change your twitter username will not affect your existing followers, direct messages, or anything. Your followers will simply see a new username next to your profile photo when you update.

Change your username

1. Click on the more  button from the navigation bar. 
2. Click on Settings and privacy.
3. Under Account, update the username currently listed in the Username field. If the username is taken, you’ll be prompted to choose another one.
4. Click the Save button.

Difference between twitter username and name

• Your username appears in your profile URL and is unique to you. It’s used for logging in, replies, and Direct Messages. 
• Your display name is a personal identifier (sometimes a business name or real name) displayed in your profile page and used to identify you to friends, especially if your username is something other than your name or business name. Learn how to change your name.

What is the length of twitter name and username

• Your username can be up to 15 characters long.
• Your display name can be up to 50 characters long.