Try Themekey module. After installing this module from 'ThemeKey User Profile' configuration, enable the option for user to select their own themes, so that it will be available in user profile and user can select their own themes.

How to allow users to choose different theme?

  （1）I get up early in order to catch a bus. 
  
  （2）I get up early because I can catch a bus.


How to ask a question according to “in order to catch a bus ” and "because I can catch  a bus"?
