I'm not sure that there is an out-of-the-box way to enforce this for guest users (but I'm checking with the team to make sure I didn't miss something).
Here are a few options, though:
- You could use Vasil Michev's script to force password changes for either a group of users or all users. Get-MsolUser -All | ? {$_.Country -eq "USA"} | Set-MsolUserPassword -ForceChangePasswordOnly $true -ForceChangePassword $true
- You could use Conditional Access to require a password change. https://learn.microsoft.com/en-us/azure/active-directory/conditional-access/concept-conditional-access-grantuse
- You could use -ForceChangePasswordNextLogin and apply it to the relevant users. https://learn.microsoft.com/en-us/powershell/module/azuread/set-azureaduserpassword?view=azureadps-2.0