By default Music Speed Changer saves your edited tracks to
Internal Storage > Music > Music Speed Changer.
This save directory is the content of My Creations, where you can easily access your prior work and any tracks you manually add to the folder. Below are step by step instructions on how to change your my creations / save directory.
Open the app main menu
Select Settings
Tap Save directory
Navigate to the desired directory or create a new directory
The arrow navigates up a file directory
Access the content in the save directory in My creations