How do I Change My Apple ID on my iPhone?

Step 1: Finding Your Apple ID Settings
On your iPhone, go to Settings and select your name at the very top of the screen (beneath your name, it should read Apple ID, iCloud, iTunes App Store).
While resetting your Apple ID password on your iPhone is a breeze, this first step is one thats easy to overlook. (Dont go looking for a list item called Apple ID on your iPhone you wont find it)
Step 2: Reset your Apple ID Password
Once youve selected your name in Settings, youll want to select Password Security on the following screen.
If the top of your screen reads Apple ID, then youll know that youre on the road to an Apple ID password reset.
Step 3: Changing Your Apple ID Password
Conveniently located toward the top of the Password Security screen on your iPhone, youll want to select Change Password. Just to reiterate: This is where youll want to go the next time you need to change your Apple ID password, your iTunes password, or your iCloud password on your iPhone.
To confirm that you do indeed want to change or reset your Apple ID password, the following screen on your iPhone will prompt you to enter your numerical passcode (unless you dont have a passcode that is).
Step 5: Entering Your New Apple ID Password
Once youve keyed in your passcode on your iPhone, type in your new Apple ID password, and re-enter it again to verify your new password.
Click on Change at the top left to confirm your new Apple ID password.
You'll also be prompted to sign out of all your devices and account if you think someone else has been using your previous password.
Step 6: Logging in with your New Apple ID Password
Log in with your Apple ID and your new Apple ID password. Now youre all set