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If you want to revoke Viable Issues' access to your Atlassian-Account navigate to the Connected apps section of your profile.
Destination Jira
Viable Issues uses the primary Jira that is linked to your Confluence. The normal case would be, that the URL of Confluence is company.atlassian.net/wiki and so the URL of Jira company.atlassian.net.
If in any case you want to define a different Jira as destination, navigate to the “Manage apps” section and configure the “Alternative Jira instance” field there.