Web tickets: When creating the ticket, select the desired tags by clicking on each one you wish to add. The selected tag will highlight in light blue.
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To unselect, simply click again.

App tickets:

1. While creating hte ticket, scroll down to the "Add tag" option
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2. Select the tag you wish to add and save; or add a new tag by typing it into "New Tag" and add

3. Now your tags will be reflected on the ticket

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