Q: how to change my iCloud ID ?

Hey PLMX,

Thanks for the question. Once you have setup your @icloud.com email address, the address is permanent and cannot be changed:

Change your Apple ID

http://support.apple.com/kb/ht5621

You can change the address of any Apple ID, except an Apple ID that ends with @icloud.com, @me.com, or @mac.com.

However, you can choose to create another @icloud.com alias:

iCloud: Create or change email aliases

http://support.apple.com/kb/ph2622

Additional information:

iCloud: Set up an @icloud.com email address

http://support.apple.com/kb/PH2620

iCloud: About your @icloud.com, @me.com, and @mac.com email addresses

http://support.apple.com/kb/HT2623

iCloud: Using your @icloud.com email address

http://support.apple.com/kb/HT5441

Thanks,

Matt M.