How do I edit/change the folder shortcuts listed in my menu?

1. Tap on the menu (hamburger icon) in the top left.
2. Once on the Menu, tap the 'Edit List' button at the bottom of the screen.
3. The screen will switch to editing mode. You can now select the folders you would like to appear. To add a folder from a specific account, select 'Add Mailbox...' and navigate to the desired folder.