Changing text on Portfolio Project page in Elemental Theme
Go to Dashboard > Pages & Themes > Page Types
For the template you are using click on 'Output'
Click 'Edit defaults'
Put page in edit mode
Click the right block and edit Title of Page List
After you edited your block you also need to click on it again and from the menu click on "Setup on child pages" or else it won't apply to already created pages, only to ones created later.