Kimai uses the 24-hour format by default.

If you want to use the AM/PM format instead, you can set the locale config key 24_hours to false to activate it. The changes need to be applied in your local.yaml.

This example uses the locale en:

            date_time_type: 'yyyy-MM-dd hh:mm a'
            date_type: 'yyyy-MM-dd'
            date: 'Y-m-d'
            date_time: 'm-d H:i'
            duration: '%%h:%%m h'
            time: 'h:i a'
            24_hours: false

After making these changes, you need to reload the cache.