To define issue templates navigate to Issue Templates in your JIRA admin panel.
General Settings - Add-ons - Issue Templates
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Issue Templates
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Here you can edit:
Group History Issue Templates can be defined dependent on user groups. It is completely optional. However if you like JIRA to Outlook to pick issue templates automatically based on the group of user, you'll have to pick all relevant groups here first.
Initial Key Selection Here you can define initial key values that are selected when user opens the "New Issue" dialog in Outlook. This can either be done for all users ( Group: All Others) or groups defined in the hierarchy above.
Issue Template Here you can define issue templates. The fields will be inserted as soon as the user selects criteria that matches the key fields. Again these templates can be made group specific if these groups are defined in the group hierarchy above.