Log in to the HTML5 client.
Select the Work workspace, Gantt tab.
Select a project in the Project Data Selector.
Select the Definition folder.
In the Stakeholders section, click on the button to open the Permissions Advanced Attributes popup.
Select a workflow in the Workflow field picklist.
Close the popup.
If a workflow has been initialized by a Project Type, the Workflow field will not be editable and will be in read-only.
This setting is defined by the Administrator.