If a sprint or release is over-planned, you may want to increase its capacity. The sprint and release capacities are derived from the estimated sprint velocities per team, as defined in the team settings pages.
To adjust a team's sprint velocity:
On the Product Backlog or Release Backlog page, in a release or team bucket on the right, click a capacity information link .
Examine the actual velocity in previous sprints and the average velocity.
In the release capacity or team velocity dialog box, use the bar chart to examine the expected and actual velocity in previous sprints, and compare them to the average velocity.
Hover over the bars to view exact numbers.
If the average velocity is greater than expected, consider increasing teams' estimated velocities.
If you're on the Product Backlog page, click the link on the bottom to the team settings page, and modify the velocity for the specific sprint there.
If you're on the Release Backlog page, you can modify the team velocity directly in the dialog box, by double-clicking the number in the Expected Velocity column. The bar chart adjusts accordingly.