Once logged into the web portal, click the "gear" icon at the top right of the screen, and select "Profile Settings".
When the window opens, you can modify various items in the first two tabs pertaining to your contact information.
When finished, click the "Save" button at the bottom of the screen. Note: if the button is not visible, you will need to scroll down to the bottom:
Once logged into the mobile application, tap the menu icon at the top left of the screen:
Select the "Profile" menu option, which will take you to your profile page. On this page you will be able to update various items related to your contact information. Scroll to the bottom and hit the "Update" button when finished.