Apple ID is the most crucial thing of your device as it is required in many troubleshoot purpose. When you do not use your Apple ID for long then it happens you forget password. In that case, you should always know the troubleshooting steps, how you can recover the old password as well as to change the Apple ID password. Here are some steps how you can change Apple ID password.
Open your safari and check out the website www.appleid.apple.com
Now go to the manage apple id option and sign-in using your Apple ID (write your Apple ID and password)
Now click on change password and select your password as well as security question. Give a reply to security questions that you can remember easily.
Now your will have the option for creating new password. Write down your old and then new password.
Now hit DONE or SAVE
Your password is changed now.