Hi Meesh2234d,
Welcome to the Support Communities!
If you have changed your AppleID information or password, you will need to sign out of your existing iCloud or iTunes Store accounts and sign back in with the new information. You will also need to authorize your computer for the Apple ID you will be using for iTunes Store purchases.
The articles below will explain this in more detail ...
Apple ID: Changing your Apple ID
http://support.apple.com/kb/HT5621?viewlocale=en_US
"...remember to update all of the features and services that you use with your Apple ID."
I have purchased music, apps, or books with multiple Apple IDs. How can I get all of this content onto my iOS device?
First, you need to copy all of your purchased content so it is on the same Mac or PC with iTunes. This computer should be the one you sync your device with. For more information on how to move your content, see these articles:
Next, authorize your computer to play content with each Apple ID in iTunes. Once your computer is authorized for all your content, it can be synced to your iPhone, iPad, or iPod touch.
iOS: Changing the signed-in iTunes Store Apple ID account
http://support.apple.com/kb/HT1311
Cheers,
- Judy
