It is rather common for a MacBook user to receive prompts for a Keychain password after the user has changed their Microsoft account. Please follow these instructions to resolve this problem:
1. Launch Keychain Access (‘Utilities’ within ‘Applications’)
2. CTRL-click on ‘login’ under ‘Keychains’ (left-side column)
3. Select ‘Change Password for Keychain “login”…‘
4. Enter your old password within ‘Current password’ field
5. Enter your currently used password within the ‘New Password’ and ‘Verify’ fields
6. Click the ‘OK’ button
7. Restart the computer and log back in – you shouldn’t notice the prompts any more