If you find a folder made by another Quizlet user that you'd like to save and study later, just bookmark it. It will be there for you next time you log into your account and you'll see any new sets that are added.
Bookmarking another user's folder
You'll see the folders that other Quizlet users have created on their profile pages. Just click on the "Folders" tab.
Click on the title of the folder and then select "Bookmark this folder."
Now the folder will appear on side bar, under the heading "Bookmarked Folders," and will be waiting there the next time you log in.
To remove a bookmarked folder, click on the folder title from your side bar and then "Remove this bookmark."
You can study or share your bookmarked folders but you cannot edit the sets in them.
Other users bookmarking my folders
Any folder on Quizlet can be bookmarked, but any private sets you put in them will not be visible to any other Quizlet user. If you create a folder with completely private sets, other users will see an empty folder with no sets.