Notification settings live under Settings and work in two layers.
Company defaults (head office) control:
Email when an application requires action — a notification when something lands in the Action required queue.
Weekly summary — a digest of the company's applications.
Personal settings let each member opt out of either channel for their own account. The override runs one way only: a member can switch off something the company has on, but cannot switch on a channel the company has off — the control is disabled and says why.
The notifications bell in the top bar is not part of these settings. It always shows the current size of the Action required queue and cannot be switched off.