If you updated your Apple ID but did not update it on your iOS device, you may see a "Incorrect Apple ID or Password" message. To sign in using your prior Apple ID, follow these steps: Tap Skip This Step and follow the Setup Assistant's instructions. Go to Settings > iCloud. Select View Account Details. Enter your previous email address and click Restore. Your data will be restored to the same state as when you left it.
It's likely that your iPhone is constantly prompting you for your Apple ID password because it's running an out-of-date version of iOS. Check to see whether an iOS update is available by going to Settings->General->Software Update. If an iOS update is available for your iPhone, tap Download and Install!
After upgrading to the most recent iOS version, your iPhone may repeatedly prompt you for your Apple ID password. This problem might be caused by a failed download or a problem with your account settings in iCloud, iMessage, FaceTime, or the App Store. If you have not done so already, please contact Apple support.
You must reset your password.
Navigate to your Apple ID account and choose "Forgot Apple ID or password." Enter your Apple ID, choose the option to reset your password, and then press the Continue button. Have you forgotten your Apple ID?
Your iTunes account is linked to your Apple ID account and can be used as an alternative way to log in if needed. To open up iTunes, click the Apple icon on your computer's home screen (it looks like a box with rounded corners) and then click the Settings menu item. In the resulting menu, look for the entry for iTunes under the Music category. The last thing you need to know about finding your iTunes password is that it's not available after you've logged out of your Apple ID account; when this happens, use one of the other methods listed below to regain access to your music library.
How to Repair an iPhone That Constantly Requests an Apple ID Password
You will be asked to enter your 8-digit security code. Enter this code and click "Submit" to have your password reset.
Navigate to Settings > iCloud. If you're already logged in, go to Apple ID > Password & Security > Change Password. And then fill in the blank with the new password you choose. If you haven't already, go to Settings > iCloud, select "Forgot Apple ID or Password," and enter your Apple ID. The system will send a message to all associated email addresses.