If you've forgotten your password, you can reset it. If you simply want to update it, you can change it from within the app.
Reset Password (Forgot Password)
On the login screen, tap Forgot Password
Enter the email address associated with your account and tap Send Code
Check your email for the verification code
On the Create a New Password screen:
Enter the Verification Code, New Password, and Confirm Password
Tap Save Changes
Change Password (From the App)
From the Home screen, open the Menu
Tap Change Password
Enter your Current Password, New Password, and Confirm Password
Tap Save Changes