Can’t Change Apple ID password with the keychain option.

When I go to change my Apple ID password on my phone via settings or on Appleid.apple.com I’m forced to type the new password in manually or copy and paste the new password in the field.

When I click into the new password box, the key chain symbol appears on my keyboard, and I’m able to click it and go into my passwords where I will select my newly created password and when I select it, it closes my password page and I will see the curser in the box act glitchy for a second and then it does nothing, and leaves the box blank?

The only way I can proceed to enter a new password is by typing it in, or copy and pasting it.

I don’t understand why my keyboard gives me the key symbol option for the new password box and verify password box if it doesn’t work?

I understand the settings within keychain and the checkmark needed to allow auto filling of the keychain, and it is on because it works for other websites and you would not see the key symbol on your keyboard if it wasn’t on.

Can anyone let me know if they can change their Apple ID password by using the keychain to automatically fill in the new password and verify the new password without copying and pasting or typing it in?

Thanks