By default, we detect your timezone automatically and store it.
To edit it, check the Personal settings section, and then General.
The second setting is the publishing timezone setting. In order to avoid confusion among the team members, this timezone is the same for everyone who manages a certain page or account.
As an example, imagine there is Francois based in Paris, and John in New York - the time difference here is 6 hours. The publishing timezone in the team is set to Paris time (GMT+1). If Francois schedules a post for 7 PM (Paris time), John will see it as scheduled for 1 PM (his, NYC time). This is because the common Paris timezone is used in this case.
To change the publishing timezone, go into the Profile Settings and then General.