Hello Dinahvanesa,
Thank you for using our plugin.
Currently "Back" button is not available in "Single Project View" however If you open the "Single Project View" in the same window then default "Back" button of the browser (or "BACKSPACE" ) will work for you. To do that please follow the below steps:
1. Login to the Admin panel (Dashboard).
2. Go to Portfolio Manager -> Settings
3. Under General Tab, Set the property "Open Project in New Tab" to "No".
4. Save the settings.
5. Reload the window and click on any of the "View Project" button, now you will be able to get back to the grid view using browser "Back" button.