First name in Leads

First name in Leads

Hello,

When Leads are created, they appear with a Lead name. 
When I want to edit the lead, only the field Last Name appears, and not the first name. 

I tried to go in Parameters -> Modules and Fields, and check if the first name was here. Actually, when I do a preview of how the lead should look, the first name appears as a field. 

I would like to be able to modify the first name when I'm in a lead. Can you help me please? 

Thanks in advance