You have two differents ways to change a picture title.
Simply enter a description by using the form field (ref: B1) and once done, validate your change by clicking on the Change button (Ref: C3)
phpGraphy is able to automatically set the picture title using the IPTC field of your choice. You can do this by editing the configuration file and setting-up the value of iptc_title_field to one of keyword listed in the EXIF/IPTC keywords reference table.