The ''server time'' displayed in the task tray of QC is based on the time of the DB server.
You see this in the lower right corner of the QC ''client''. Since they are both in the same time zone, the QC ''server'' and DB ''server'' are the same time.

Now for your Client users in a different timezone.
QC ALWAYS stores the SERVER time in the DB records for various date/time stamps, it is always the same reference time zone - the one used by the DB-Server.

So, the Detected on/Created date (Date only, no time) is from the SERVER and the Modified Date/Time is from the SERVER.

Example: if you created a defect at 8AM in Melbourne, it picks up the SERVER time (Denver) and automatically suggests a DATE for Created/Detected-on.
Because of crossing the International Date Line (backwards), when it is Morning in Melbourne, it is Afternoon the PREVIOUS DAY in Denver (at the same time).

But, you can change/select the Detected on Day at Defect creation time if you want.
The blue-highlighted day on the ''calendar selection pop-up'' is the Server Day, and ''today'' is according to the client. If you are in the same time zone as the DB-Server, they are coincident.

If someone with a Melbourne client selected ''today'' in Melbourne, the Detected On date would be AFTER the modified date - even though it was never modified yet - just saved.
Then during the day, any modifications made would still appear to have happened before the record was created (up to the hour when the time zones catch up to be the same date).

We cannot change this.

When a record is created, it only captures the DATE (with a constant default time of Midnight) defaulting to the ''today'' from the Server, but can be selected to be any day as you create the record. Then after it is saved, you cannot change the Created/Detected On date.
As modifications are made to the record (i.e. Defect), QC captures the DATE and TIME stamp from the SERVER.

Just know that there is only ONE time zone used when saving dates on the server, and when scrutinizing time/date stamps, one needs to know wher the DB server is located (time zone it uses) for a reference.