Hi nolw,
My apologies that this is not clear as of yet. In 0.2.0 I have tooltips coming to make it more clear as well as visual feedback to show it's been saved.
When you are in the Editor (make sure you click Edit) in the Library, there is a tiny "save" icon on the top right.
Once you click that you should see a pop-up that enables you to save info. After that, click the "save" button at the bottom of the pop-up. Your changes should be reflected once you go to the Library again.
Here are screenshots to show the locations: https://imgur.com/gallery/2MYz...
Let me know if you have any other questions!
Thanks,
Phil