Forgot want to rest password
Want to reset password forgot old one
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You'll need to recover the old one before you can change/reset it.
See If you forgot your Apple ID password https://support.apple.com/en-us/HT201487
You also can use Having trouble signing in/iForgot https://iforgot.apple.com/password/verify/appleid
And you almost certainly will need to see If you forgot the answers to your Apple ID security questions https://support.apple.com/en-us/HT201485
Before trying to answer your security questions is very important that you think about your questions and their answers carefully and try to recall all details you can. If you don't answer them correctly enough, then you easily can lose control of your account.