Users can associate a number of Scans under a single Jira Project.
After Creating a Jira Connection, Create a New Project, and choose the desired Jira Project Key :
Then, when initiating a New Scan/s, in the Settings tab, choose the Project :
You can also do that after the scan has be initiated. To do that, navigate to the Settings tab in the Target Details, choose the desired Project and click on Set Project :