Hello José Segura,
You can't do it at Cloud Version. And there is no workaround for it.
And I couldn't find issue to improve it.
https://jira.atlassian.com/browse/CLOUD-8511?jql=summary%20~%20%22outgoing%20mail%22%20and%20project%20%3D%20%22Atlassian%20Cloud%22
Regards,Lameck.
You can edit the mail subject prefix through JIRA administration -> System -> Outgoing mail.
I'm afraid that's a restricted function on Cloud.
You will need to raise this with Atlassian Cloud support, but I don't know if they will change the prefix for you.
It looks like you're new here. Sign in or register to get started.