How do I change my iCloud password

Change the Apple ID password from device Change your Apple ID password - Apple Support

1. Tap Settings > your name > Password & Security.
2. Tap Change Password.
3. Enter your current password or device passcode, then enter a new password and confirm the new password. Forgot your password?
4. Tap Change or Change Password.

Changing of password is done when you already knew it , if you don't remember it then reset it If you forgot your Apple ID password - Apple Support

I need help you all. It’s telling me to enter my password to down load an app. I just opened a new bank account and I need to download the mobile app but I can’t get no information about my mobile account because I can’t download it because I need my password