$ apropos timezone
tzconfig (1)         - set the local timezone
tzselect (1)         - view timezones

just view it, make some suggestions, doesn't change system setting

do the changes (menu directed):

/etc/timezone
/etc/localtime

$ file /etc/timezone
/etc/timezone: ASCII text

$ file /etc/localtime
/etc/localtime: timezone data

Use

zdump -v /etc/localtime

to view its content.