How can I change my iPhone's passcode?

Which option are you not seeing in this support article?

Set a passcode on iPhone - Apple Support

If you have Screen Time turned on or your device is remotely managed by a company or school, then you may have restrictions set that will not allow you to change your Passcode.

Screen Time can be turned off by going to Settings > Screen Time. If your phone has been set up with Family Sharing, then the Organizer that set it up will have to make the change.

If it is a company or school device used by you, then only they would be able to unlock it to allow you to make that change.

thierer1114 Said:

"How can I change my iPhone's passcode?: So I've been trying to change my Passcode to my phone and, when I go to settings I don't not see the setting to change it at all"

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Changing he Passcode:

One option...

Reset it:

Enter the passcode incorrectly too many times, and you'd likely be locked out for good. So, hold it right there, and refer to this link: If you Forgot the Passcode on your iPhone, or your iPhone is Disabled - Apple Support.