If for any security you want to change the apple id password in IOS 7 then you can do it easily by following the steps mentioned below.
At first logon to this website “https://appleid.apple.com/cgi-bin/WebObjects/MyAppleId.woa/”
Click on “Password and Security” link on the left side.
Now you need to answer the two security questions as shown on the right side and click on “Continue” button.
You will get the following screen for changing the security setting for your Apple ID.
If you have successfully changed the password then you will get a message.
This is how you can change your Apple ID password in IOS 7.