How to change your Twitter password on a phone:
Open the Twitter app on your iPhone or Android phone.
Next, tap your profile picture at the top of the screen.
Then in the Twitter sidebar, select Settings and Privacy.
Now on the Settings and privacy page, tap Account, followed by Password.
Enter your current password and then type the new password in the new password, then Confirm Password fields.
Finally, click Done to confirm your intention to change the Twitter password.