If you click on your photo icon in the upper right corner of the screen, then "Settings" -> "Notifications" you can adjust the following settings:
Change how often you receive a daily email digest - daily, weekly, or none. This email digest will include new posts in your communities, as well as if posts you are following received new comments.
Change how you want to receive notifications about new comments on posts you are following. You can receive notifications via email, mobile, by both email and mobile, or no notifications.
Change whether you want to receive direct messages (DMs) by email, mobile, or by both.
You can turn on or off push/email notifications individually for each group you are a part of. Simply click the downward arrow adjacent to the group and toggle on/off notifications by mobile/email.