From the main page of Ticketing, you can access the My Activities menu option. Please check your general settings in case the activities option is not shown.
Under My Activities you will find a list of workflow actions assigned to the currently logged in person, or one of the groups this person belongs to. Please note that ticket assignment fields have no influence on displaying tickets here.
Use the button "change actors" to quickly change the person or group a workflow step is assigned to:
After clicking this button the ticket will open and the workflow reassignment popup is shown: