Any project-scoped properties associated to the selected workflows or instances will be displayed in the Project Properties section. You can override Instance level properties by clicking on the Override Properties button.
A required property is indicated with an asterisks to the left of the Key Name. By clicking the button between the Key Name and the Value, you can toggle the value between being a literal value 
and an expression 
.
You can filter the displayed properties by entering part of the Key Name into the Filter text box and clicking the Filter button (filters using contains operation). By clicking on the clipboard icon 
to the right of the Key Name, you can copy the Property Name to your clipboard.
For information on configuring these project properties see the Properties chapter Editing Project Properties