In the test case details window, the version marked as the current version will be indicated by a green checked icon in the dropdown list. To mark another version as current, select the desired version from the drop down so that it is the current version on display. Click on Next Steps , and select Mark as Current. The version should now have the green checked icon. Test cases that only have one version will not have this button available.
Users will need view and edit permissions for test coverage to perform this action.