iCloud keychain problems - asking passwords, can't change password, can't unsync
Solution 1:
Sorry to bump an old thread, but I found this simple solution. At least in my experience, the password for the default keychain cannot be changed, so:
1) Create a new keychain (File→New Keychain… ⌥⌘N). I named it temp and gave it a simple password.
2) Right-click the temp keychain and select Make Keychain “temp” Default.
3) Select the original keychain.
4) Edit→Change Password for Keychain [name]… should now be accessible. Select it and change the password to your heart’s content.
5) Right-click the original keychain and select Make Keychain [name] Default.
6) Right-click the temp keychain and select Delete Keychain “temp”
Solution 2:
Not sure if you ever found the solution, or if Mark's solution worked for you. I recently ran into this issue, and followed the steps at https://scatterbin.blogspot.com/2018/08/change-password-for-keychain-local-items.html and it worked for me.
It seems to be a little known solution, and it took me a while to find this.
From the page:
The following steps should allow you to change the Local Items keychain password, provided that you know your old password.
Restart your Mac. When prompted to enter the password for the "Local Items" keychain, click on Cancel and do not enter your password. Note: you may be prompted multiple time and need to click on Cancel multiple times. Open up Keychain Access (you can look for it via Spotlight). Lock the "login" keychain (yes, the "login" keychain). Unlock the "login" keychain. After unlocking the "login" keychain, you should now be prompted to change the password for the "Local Items" keychain. Change the password to match your user account password.
Solution 3:
I had the same problem, also tied to using my iCloud account to login.
I was able to resolve the issue by going to System Preferences > iCloud and deselecting 'Keychain' from the list. This reverted the "iCloud" keychain to "local items" in Keychain Access.
The next time the "unlock local items" pop-up appeared, I entered the password and got another pop-up asking me to change my password (enter old, enter new, re-enter new).
I changed the password there to match my login password, logged out and then back in again, and haven't received anymore notifications.