The way tasks and processes are managed in Jira is through workflows . A workflow maps out the statuses an issue can go through and the available transitions between these statuses that together define your entire process. 

You can edit the overall workflow used in a project, or modify the way particular issue types are handled in their workflow. But: At some point, you might end up stuck in the middle of nowhere because of feature limitations.

At this point, Jira Workflow Toolbox for Jira Cloud (JWT) comes in handy!

JWT for Jira Cloud enhances the way you configure workflows. It extends the native functionality by offering custom conditions , validators, and post functions.