I would like to set the language to English (Australia) however that option does not exist in the language settings for Jira. We really need to display the dates in DD/MM/YYYY format as the US format (MM/DD/YY) can be very confusing here.
Australian English is not available on Cloud I'm afraid, but it's a lot closer to English than American English is, and the main differences are in words you probably wouldn't find much in an issue tracker!
Obviously, the date format is also correct, so you can get very close to Australian English this way.
Cloud:
https://support.atlassian.com/jira-cloud-administration/docs/configure-the-look-and-feel-of-jira-applications/
Server:
Administration > System > Look and Feel >Date/Time Formats
It looks like you're new here. Sign in or register to get started.