Use Sprints for Manual Scheduling

When the Use sprints for manual scheduling option is selected, tasks can be scheduled to begin and end based on sprint dates.

When sprints are used for manual scheduling:

Tasks assigned to sprints are scheduled for the duration of those sprints, based on current sprint dates and future sprint estimates.
Work for each task is evenly distributed across its sprint duration.

For more information about sprint-based scheduling, see Planning with Sprints.

Prefer sprints over manual start and finish dates

If this option is selected, issues assigned to a sprint will automatically be scheduled based on that sprint.
If this option is not selected, issues with manual start or finish dates will be scheduled based on those, regardless of their sprint assignment.

To learn more, see Scheduling Precedence.

Backlog Board

Issues that are not assigned to a sprint (and do not have manual start or finish dates) will be placed in the Backlog panel, rather than on the timeline. You can assign those issues to sprints by dragging them onto the chart or using the Task Details Panel.

The available sprints will be based on the selected board.

You can only select one board for the backlog. If your chart includes issues that need to be assigned to sprints from another board, you can assign specific boards for each project using Slices.