At the moment the Time Zone is set on a User by User basis and this cannot be amended by an Admin. This has resulted in having users in both a London GMT Zone and Central American Time Zones. Which is making it difficult to track when Ideas have been raised. Would like the ability to set Time Zone on a System wide basis and Users can manually amend this if required.
As you mentioned, Time zones are set on a user basis. This is intentional as it allows the information in the application to be directly understood on a user basis (regardless of where other team members are). For example, users in the London GMT time zone will see idea times based on their own time zone (and same for Central America time zone users).
At this point, we do not have plans to make updates in this area. We hope you can understand.