In Confluence you can configure an application link to Jira. After doing so you can define under Space tools --> Integrations --> Application Links a related JIRA project for a Confluence Space.
I would like to have the Issue Manager considering this configuration, so that when I create an issue from text (using the Issue Manager Pop-up) or when I click the "Create Issue" button in the page navigation menu the linked JIRA project is selected by default.