Hi Davide,
Unfortunately there is no way to change this timer. The following link outlines information relating to Offenses and retention
https://www.ibm.com/support/pages/qradar-information-about-offense-duration-retention-and-activity
Should this be functionality that you require you can submit an IBM idea
https://www.ibm.com/support/pages/welcome-ibm-ideas-portal
Thanks
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John Dawson
Qradar Support Architect
IBM
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