In general the timezone is configured in the user profile of each
user, so changing the server timezone has no effect how to the users
calendar for example.
However there are some circumstances where there is no user profile available.
Goto Administration > Configuration and change the config-key: default.timezone
Valid timezone have to meet standards!
in the public/config.xml change the key:
<!-- First day in the Week used by the Calendar 0 means Sunday 1 means Monday this is the way how the Celendar inits a week --> <firstdayinweek>0</firstdayinweek>