Apart from editing Checklists while editing a JIRA issue, you can as well edit them in the Agile boards. Every change that you make to the Checklist in an Agile board is immediately committed. You do not need to click any Submit button to commit your changes.
Hence, it is recommended that you exercise caution before changing or deleting an item as such changes cannot be undone. If a Checklist is visible on the issue screen and the Checklist custom field context includes the currently selected issue, the Checklist is displayed in the details view under a specific panel.
The number below the Checklists Panel icon indicates the number of Checklists displayed in the panel. If more than one Checklist is available to the selected issue, each Checklist is displayed on top of each other with their name in the header. If no Checklist is available, the panel is removed from the details view.
The entire Checklist is saved when an item is changed. Custom fields work in a last saves win scenario, implying that if two users simultaneously try to save a custom field, the user who saves the changes later will overwrite the changes made by the previous user. Hence, if multiple users work on the same issue and the same Checklist, there is a possibility of conflict. However, this is an unlikely event as JIRA periodically refreshes the board and forces a full refresh of the issue when the browser receives the focus.