To see your Notification Settings, navigate to "Account Settings" by clicking on your avatar in the top-right menu and selecting "Account Settings".

To make changes to your Notification Settings, check or uncheck the desired options. 

Note: if your Admin has disabled a notification setting at the company level, you will not be able to enable it and the checkbox will be grayed out.

Clear All Notifications

To clear all of your notifications at once, click on the bell icon next to your user profile image and click "Mark All as Read".