There are two levels of notifications: General Notifications and Group Notifications. General Notifications refer to platform-level messages and alerts, while Group Notifications refer to messages and alerts that are sent to you from the Groups for which you are a member or a Group Officer.
To set your notifications, select your profile in the top right and select Notification Settings.
Tip: If you are a Group Officer, you may receive notifications when a user has requested to join your Group and needs validation. If you would like to stop receiving these alerts, under your Group’s Officer-Only Notifications, uncheck notifications for the setting, New member requires validation.