Display Name in Contacts app

How does the ownCloud Contacts app generate the display name from the contact information:

Problem: I use the Contacts app as a central for synchronizing my local contacts on different devices, including MS Outlook on my Windows PC (using CalDav Synchronizer software), my iPhone, and the phone book of my Fritz!Box internet / VOIP router. Contacts are mainly maintained in Outlook and then synchronized with my other clients via ownCloud Contacts.

Contacts usually include a first name, a last name, and most have a salutation (Mr. or Ms.). First and last name are synced from Outlook to the appropriate fields in ownCloud Contacts and the salutation is synced to the Prefix field. However, for reasons that I cannot understand, the form of the display name in ownCloud Contacts differs between the contacts: some appear as

Salutation FirstName LastName, others as
FirstName LastName (even though a salutation is present in the contact), and still others as
LastName, FirstName (which would be my preferred display name).

I know that I can set the sort order of the contacts in the settings of the Contacts app. However, it appears that the display name is passed on to other CardDav clients during sync (e.g., to the phone book of my VOIP router) where it determines the order in which the contacts are shown.

How can I set configure the display name to consistently use the form “LastName, FirstName”?

Kind regards, Andreas