Sony Xperia User Manual page 338

City list opens.
Tap city to add
City is added to world clock screen.
World Clock Operations
Setting Home City
In world clock screen,
Switching Celsius/Fahrenheit
In world clock screen,
Rearranging Cities
In world clock screen,
Deleting
In world clock screen, Touch & Hold city
23
Set home city Tap city
Fahrenheit/Celsius
Rearrange Drag
YES
up/down DONE