Let us start this topic with a scenario…
Suppose XenApp machine is placed in the data center located in New York and many applications are installed/configured and published from it. This application has users throughout the globe. Now since the application will always be executed at XenApp kept in New York, what time zone it will assume if the user who is accessing it, is located in New Delhi?
Ideally users in New Delhi should see their own time zone as they don’t care about the location of XenApp and the data center but the application will take XenApp time zone setting as it is executing on that machine.
To resolve this time Zone issue, Client time zones setting can be done on farm level settings. To do so, go to the Farm properties, expand the Farm wide > Presentation Server node and select the General node. From the time zone settings panel, check “Use Client’s local time” and then apply the change. This is shown in the below screen shot:
Now next time when user will access his application, the application will read his local time zone settings.
Mohd Aslam's Blog 