If you're experiencing trouble saving projects, here are some suggestions on how to fix it.
Size of Sound or Image: If a sound or image is larger than Scratch's maximum file size (10MB), then the project won't save. If you cut the sound into smaller pieces using the sound editor, then it should save.
To cut a sound into smaller pieces, try this:
1) Click the Sounds tab and pick the music or sound file that's long.
2) Select a section of the sound, starting from the beginning.
3) Click the "Copy to New" button. (If it doesn't create a new sound, the piece is too large, so select a smaller region.)
4) Select the next section of the sound. Click "Copy to New" again.
5) Repeat the process until the whole sound is broken into pieces.
You can now play the sounds one after the other. Click the Code tab. Snap together "play sound until done" blocks to play each of the sounds in a row.
Project File Size: Another thing that can cause a project to not save is if it is a particularly large project with lots of sprites and code. Scratch stores information about the project in a file called project.json which has its own file size limit of 5MB. If you have a file with many sprites and lots of code, try using fewer sprites or fewer blocks.
Internet Connection: A project may not save if you lose internet connectivity while trying to save.
Signed Out: Another thing that frequently causes people to be unable to save is if their account gets signed out. This can happen if an account is signed in to more than one computer or if more than one account is signed in on the same computer. It usually happens when someone is working both at home and at school, if more than one person is sharing an account (which we don't recommend), or if two people are working on the same computer.
To prevent getting signed out, don't share Scratch accounts with others and only sign into one computer and account at a time. Also, make sure to sign out when you're done using Scratch on a school, library, or other shared computer.