How to set default time zone for new users? / Times and relatives times incorrect

Hi there,

just have 2 qeustions related to time zones:

I've noticed that the default time zone for new users is GMT. . As most of the new users will be in Singapore at the moment, I would like the option of making that as the default time zone, so users do not have to adjust it UNLESS they are not from Singapore. How can this be done?

Despite this, there also seems to be a problem. where the times are not being made relavative to the time zone you are in. EG my time zone is set to Sinagpore time GMT + 8 hours. . when a new user signs up and is set to GMT, in the activity streams, it is showing up that they signed in not just a few seconds or minutes ago, but 8 Hours ago. how can this be corrected?