How do I change the phone number associated to my keychain?

You are a god. For months this stupid thing baffled me, within mere seconds, a wave of pure and inequitable joy has hit me. THANK YOU!

I called Apple. and the guy told me strait out that the phone number couldn't be changed. It didn't matter if the phone had been run over by a semi, had been stolen, lost, or was discarded, the security feature of iCloud prevented it. We screen shared, and I was even speaking to his head supervisor. The only solution that they could come up wt was turning off my keychain, so that I would stop getting the "verify the the two step verification" message. I don't know how any of you were able to change the phone # associated wt your account? I have a speech impediment, that makes speaking difficult, and spent an hour on the phone wt them. It wasn't an easy hour ...

I believe apple needs to train their staff .

All you need to do is when enter iCloud keychain it will ask for a code choose you forgot it then choose reset keychain. that is all.

At first I had the same problem. When i went to Settings > iCloud > enable the iCloud keychain > Approve the Security code, then it sent the verification code to my old phone number. Then i clicked "Don't have access to this phone?", it said "If you do not have access to this phone number, you can verify your identity with Apple Support.". So, i tried to contact Apple Support. They said would call me back tomorrow to help me solve the case.

but.....

i cancelled the call. Because, finally i found the solution by myself before they call me!

I went to Settings > iCloud > Apple ID > Password & Security > turn on "Two-Factor Authentication", then i tried to change the Trusted Phone Number (i rewrite the same phone number)..... when i tried to enable iCloud Keychain again, then it works!!

Please I want to back up my photos

Thankyou!!!

IsackH