Access permissions in Wealthbox are employed to restrict access based on the visibility setting associated with each contact or CRM activity, rather than from the user's profile or account perspective.
For various data entry interactions in Wealthbox (eg. adding contacts, tasks, calendar events, etc.) there is a “visible to” option, also known as “permissions” which allows users to make information visible to “everyone” or “only me” or a "group" of users. In the Settings section, you can create groups of users within one CRM workspace account.

Can I set a default permission?
Yes. See: What are default permissions and how do I set them?
What happens when I update a contact record's visibility?
When a contact’s visibility is updated, the contact record and any new activities added to it will follow the new visibility setting. However, past activities will still appear in the homepage activity stream according to the visibility that was in place when they were created. Keep in mind, only users included in the new visibility setting will have access to the contact record and any new CRM activities moving forward. See also: How Do I Restrict Access To Contact Records?