How do I change the APPLE ID on my device

To change an Apple ID on your device to another existing Apple ID you simply need to log out of the old one and back into the new one. Go to settings on the iPhone, click on your name at the top, then scroll down and log out. Then sign in with the new one.

Sign out of iCloud on your iPhone, iPad, iPod touch, Apple TV, or Mac - Apple Support

Finding the best solution would depend upon our knowing the details of the situation. For example, there are a few places where you can use a different ID on a phone signed primarily into one ID.

Simply signing in and out is a possibility but may call for a complete erase of the device between users to prevent mixing of content. See What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support

Read this document to learn how to sign out of iCloud on your iPhone, iPad, iPod touch, Apple TV, or Mac --> Sign out of iCloud on your iPhone, iPad, iPod touch, Apple TV, or Mac - Apple Support

For an Apple mobile device:

1. Go to Settings, then tap your name. 

2. Scroll down to the bottom.

3. Tap Sign Out.

4. Enter your Apple ID password and tap Turn Off. (Read this if you If you forgot your Apple ID password - Apple Support ) 

5. Turn on the data that you want to keep a copy of on your device.

6. Tap Sign Out.

7. Tap Sign Out again to confirm that you want to sign out of iCloud.

Read this support article to learn how to sign in with your Apple ID on different devices--> Sign in with your Apple ID - Apple Support

For an Apple Mobile device:

1. Open the Settings app.

2. Tap Sign in to your [device].

3. Enter your Apple ID and password.

4. If prompted, enter the six-digit verification code sent to your trusted device or phone number and complete sign in.

Again depending upon the scenario, you may find Family Sharing may suffice to meet your needs.

What is Family Sharing? - Apple Support

Manage Family Sharing settings - Apple Support

Set up Family Sharing - Apple Support

On the device you want to change simply logout of that Apple ID and log back in with the new Apple ID. But remember, all the apps, purchased music or movies, subscriptions, will no longer be accessible with the new Apple ID. All of your purchases are tied to an Apple ID.