The technicians that are listed in the Resources section depend on the Branch that you have access to. Marking the check box checkbox to the left of the technician name in the Resource window will update the Schedule Board and the Unscheduled Appointments section with the technicians' appointments. You can select all the displayed technicians by marking the checkbox to the left of the Search box. When you exit out of Schedule, the technicians that you have marked are saved and when you launch Schedule, they will still be marked.
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To refresh the Resource list, select the Refresh 
icon at the top of the section. This will refresh the list back to its last saved state. Additionally, if any new technicians have been added or inactivated in Signature, they will display in the list.the technician list will be updated. These changes may be visible to you, depending upon the currently filtering of the Resources in the Resource panel.