Currently, Zephyr for JIRA does not let you customize the columns seen on the Test Cycle Summary screen. However, you can add and remove columns from the ZQL Test Execution Search reachable by clicking on the Test Cycle name in the Test Cycle Summary Screen.
1) First Select the Test Cycle Name from the Test Summary screen
2) You will now be in the Search Test Execution screen with a pre-populated search filled with the executions of the selected cycle. While not able to add or remove more columns, you will be able to view more columns for each execution than you could from the Test Cycle Summary screen, ie: priority, version, cycle name, project name, and creation date
Note: You can refine or expand the search from this page by adding or removing filters from the search bar, respectively