By default, the client name format is set as "First name Last name". It doesn't matter if the Second name and salutation fields are completed.
But what if you need to change the client name format? For example, you need the second name to be displayed too. Go to CRM > Settings > Other > Other Settings > Format and select the Client name format (for leads and contacts) you need:
Click Apply to save changes. The client name format is successfully changed.