In WordPress Dashboard go to the Appearance submenu and click on Customize.
After clicking on customize you will in theme Customizer.
Here you have to click on Page Template than Portfolio Page
In Header Here you can manage the Title, Subtitle & Description
Go to Customize -> Page Template ->Porfolio Page -> Header
In WordPress Dashboard go to the Appearance submenu and click on Customize.
After clicking on customize you will in theme Customizer.
Here you have to click on Page Template than Portfolio Page
In Content Here you can manage the No. of Post Display
Go to Customize -> Page Template ->Porfolio Page -> Content
You have to use Portfolio Image Size 717Px X 717Px