How do I limit what users can see based on roles, and how do I hide records that belong to other users?
In order to restrict users from seeing other people's time, please assign the Team role to the users who should only be able to see their own time:
With the Team role, they will have access to only their own data.
More on user roles is available here: User roles general info.
You should keep in mind that on the work item form 7pace Timetracker tab, any user can see activity from other users, however, they see only a summary and not the exact worklogs.