You can find these two titles in these files:
-\includes\view\portfolio\single-container.php
-\includes\view\portfolio\single-floating.php
-\includes\view\portfolio\single-fullwidth.php
-\includes\view\portfolio\single-gallery.php
According to the type of portfolio you are using, you can edit only one of these or if you want, edit all of them.
Let us know if you need further help.
Sorry for the late reply.
You can access these files only via ftp. Go to your wordpress installation files and follow this path:wp-content\themes\tower\includes\view\portfolio\... in the last folder you will find all above files.
As i wrote above, these two titles are hardcoded and so you need to edit them from theme files. Go to file \includes\view\portfolio\single-gallery.php, edit the titles here (screenshot).
Or translate them via .PO/.MO files.
