How-To: Change Location on the Weather Widget.

By default the clock widget displays the local weather. If you wish to see the weather for another location:

1. Tap and hold the Clock widget.
2. Drag the Clock widget on top of the "Edit" button.
3. Select the desired city.
4. Tap the "Add" button depicted as a "+" in case you can't find your city in the list.
5. Press "Done.

NOTE*: If you so desire, you could add more than one Clock widget to your Home screen or a different Home screen panel.

How-To: Set an Alarm, Change Clock Settings and use the Clock Application as a World Clock.

Accessing the Clock App:

1. To access the clock app tap the "Apps" icon found on the Home screen then select "Clock".

World Clock Settings; Setting Your Home City:

1. On the "World Clock" tab press "more", the icon depicted as three vertical dots.
2. Select "Home settings".
3. Browse the list and tap your home city.

World Clock Settings; Adjusting Time and Date Manually:

1. While on the World Clock tab press the "more" icon then select "Local time settings".
2. Uncheck "Automatic time zone" and "Automatic date & time".
3. Set the desired time zone, date and time as you desire.

See More: Using the Clock App on Your HTC One S