Who sees what is the access grid for your Travel Agency team, in Contacts → Team, right below your staff list. Only the agency owner sees or can change it.
Rows are your teammates. Columns are your clients. Click a cell to cycle it through three states:
No access: this person cannot see this client at all. Nothing about them shows up anywhere for that teammate: no bookings, no schedule, no clients screen entry. This is the default for a cell you have never touched.
Operational: this teammate can work the client: bookings, schedule, rooming, RFP room rates. They see what a flight or hotel costs (they need that to book it), but not what YOUR agency earns on it.
Operational + Money: everything above, plus your agency's own commission and coordination-fee numbers on that client, and that client's invoices.
Travel documents: a separate switch per teammate, off by default: whether they can open passports and other travel documents (only for travelers on clients they can see). See the Travel documents topic.
A brand-new teammate starts with every client at No access. You opt them into a client, and separately into your money on that client. Never the other way around. A new client you add is visible to whoever added it right away (there is nothing to grant yet for something that did not exist a minute ago), but nobody else sees it until you put them on the grid.
This is enforced on ATOM's server, not just hidden in the app. A restricted teammate's own session simply never receives a client or a commission number they were not granted, so there is no way around it from their side.