To rename a custom folder, please follow these steps:
Open the Insight Timer app.
Tap the Saved tab (fifth icon at the bottom of the screen).
Select the Folder you would like to rename.
(If you do not see the folder, tap Edit in the top-right corner to add it to your shortcut list.)
Tap the three dots (⋯) in the top-right corner.
Select Rename Folder.
Enter your new folder name.
Tap Save.
Your custom folder will now be updated with the new name.