From the navigation menu icon, tap Settings and privacy.
Tap the Account tab and under Login and security, tap Password.
Enter your Current password.
Choose your New password.
Save your changes by tapping Save.
Note: If you're able to log in but can't remember your password, you can send yourself a password reset email from the password settings page. Additionally, you’ll be logged out of all your active Twitter sessions, except for the one you use to change your password.