If you are unable to access advanced form settings in Microsoft Forms, here are a few things to try:

1. Check that the user account has the proper permissions to create and edit forms.
2. Make sure the user account is enabled with the Microsoft Forms Pro subscription.
3. Double-check that the settings are enabled properly in the Office 365 or Microsoft Portal.
4. Verify that the browser supports the use of the Microsoft Forms portal.
5. Log out and re-login to your Microsoft account.
6. Clear the cache and cookies from the browser.
7. Check for Firewall and Antivirus software, as well as any internet connection issues.