When adding tasks to the task list on the project overview, you can assign one or more team members to each task:
When one or more users are assigned to a specific task, only they can enter time against that task. The task will not appear as an option in the dropdown of the Track view for unassigned members.
When no one is assigned to a task, all project members can enter time against the task.
Team members will be able to see assigned tasks with their descriptions in their Track view:
They can simply start tracking time on any assigned task by clicking 'Add time log' for a task from the list.