Global Project USER
Working hours can be set at three different levels:
The Global setting (Jira settings > Apps > Clockwork configuration > Working Hours) allows you to enter the working hours for your organization.
You can also set work hours for a specific project (Project settings > Apps > Clockwork > Working Hours).
An individual user can configure their own Working Hours, by going to Apps > Clockwork in the main Jira menu and selecting Working Hours.
Clockwork timers will always use the most specific Working Hours available (assignee, then project, then global).