The times displayed in JIRA for issue creation, comments, etc. do not match the system time on the machine running JIRA.
JIRA persists date/times in the database in the timezone that the Java process running JIRA returns. This means if the timezone changes, the data can be stored in different times. Additionally when restoring an XML backup from another server, if the timezone changes this can alter all the times in the database. This is covered in further detail in JRA-26039 - Verify the system timezone when an XML backup is restored Closed .