The "neworder.pref" file is where Serato saves your crate order information, if you're experiencing issues with your crates reordering each time you open Serato DJ it is possible this file has become corrupt.
Creating a new "neworder.pref" file will reorder your crates into alphabetical order and any changes you make to the order should save for the next time you open Serato.
If on a Mac: Open Finder and Navigate to Music -> _Serato_
If on a PC: Navigate to My Music -> _Serato_
Move the "neworder.pref" file from your _Serato_ folder to the trash, the next time you open Serato DJ it will generate a new "neworder.pref" in your _Serato_ folder because it is unable to find the old, corrupted file.
If you're still having issues with your crates submit a help request