for iCollections from the App Store (App Store version)
rm ~/Library/Containers/com.naarak.Collections/Data/Library/Preferences/com.naarak.Collections.plist and press Enter key.
4. Enter the following command:
killall -u user_name cfprefsd (replace user_name with your Mac login user name eg. john) and press Enter key. You can find your login user name in the System Preferences/User & Groups: