An epic can span issues across several Jira projects, Users can change an epic's colour in both Kanban and Scrum projects, and Users must turn on the Kanban backlog to manage epics on a Kanban board are correct.

Epics are a normal issue type and they can be used to group work across projects when your board filters and project permissions include those projects. This makes it possible to track a single large initiative that spans multiple teams and projects.

The ability to choose and change an epic's colour is provided on the epic panel and in the backlog or board views for both Scrum and Kanban boards. Changing the colour helps visually group issues that belong to the same epic on backlog and board views.

Kanban boards do not enable a backlog by default and the Kanban backlog is a configurable feature. You must enable the Kanban backlog to get the backlog view and the epic panel that helps you manage epics on a Kanban board.

An epic cannot be converted into a subtask is incorrect because Jira provides issue type conversion and move options that let you change an epic to other issue types when appropriate, and with the right steps you can convert or move issues into sub-tasks depending on your configuration.

An epic may contain another epic through an epic link is incorrect because the epic link is intended to associate standard issues like stories and tasks to an epic, and it does not create nested epics. Creating hierarchical relationships between epics is not supported by the basic epic link, though portfolio tools add different hierarchy fields.

An epic is unable to have its own issue screen is incorrect because epics are issue types and they can have their own screens and field configurations through the normal screen scheme and field configuration settings.

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