I'd like to check whether I understand correctly the settings for:
Administration -> Users -> User Policies -> Full name format and Alternative full name format.
The original setting, "language", works fine, and all the names are displayed as "firstname lastname".
As an admin, I changed the setting values from "language" to:
* Full name format: firstname
* Alternative full name format: firstname lastname
hoping that users like guests or students will see only the firstname, while teachers will see both firstname and lastname.
I went to one of the forums, and the teacher also sees only the firstname, instead of firstname lastname.
I checked the permission of this forum, and see that teachers have "Always see full names of users (site:viewfullnames)" permission. 
Shouldn't this mean that the teachers will see the alternative full name format (firstname lastname)?
Is this a bug, or I'm doing something wrong here, or not understanding the point?
Thanks,
Ivana
(I used the Moodle 4.4. sandbox demo site to check this)