Technician only one than can Edit change

Technician only one than can Edit change

We have a big problem as we are trying to upgrade to Version of Servicedesk plus. We have technicians that are assigned changes but occasionally technicians leave, and we need to reassign the technician who will work on the change.
 
Currently not even the sysadmin can edit a change? How can we change the technician of an already assign change.

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