To edit an existing list you'll need to be the list owner or added as a list contributor.
Once added you can make edits to the overall list, any sections or any items in the list.
Ensure that your list is associated to the module. To link the list to a module, click on the three dots (ellipsis) to open the reading list options menu and select Manage link to module or select Link to Module at the top of the page.
Edit the list details by clicking Edit list.
Make your changes and select Save.