You can set default project participants when creating or editing a project card.
Then, when creating a new task in a project, Planfix will suggest adding the users from this list as task participants. The task creator will be able to agree to the list of participants or edit it.
When is this useful? If you have to provide the same people with viewing access to many of the project's tasks, setting this list of participants at the task level will make things easier and save you time: the assignees you need will be added to the task by default.
Having default project participants doesn't guarantee that these participants will see all of a project's tasks since task creators can exclude certain participants from the list manually when creating a task.
If you click the checkbox below the list of participants when adding default participants to a project:
they will be added to all tasks in the project that are active at that time. This lets you give them access to existing tasks without any additional steps