To make changes to your custom lists, click on the Settings cog.
Once on the Settings screen, select 'Configuration' and scroll down the page until you reach 'Custom Lists.'
Click on the arrow to reveal the dropdown list containing all of your current custom lists. Please note: your custom lists may not contain the same lists as the image below.
Simply select the custom list you would like to remove an item from or add an item to. To remove an item, click 'Remove'
If you wish to add an item, type your text into the 'Type new list value' car and press 'Add.'