Well, there are no 'default units' in CloudCompare. CC displays the values / coordinates / distances / etc. in the same units as the one present in the file you have loaded.
But if you want to change them, you can use the 'Edit > Multiply / scale' method to convert the coordinates to something else (of course you'll need to know what are the original coordinates... but only you can guess it as it's not written in the file).
Daniel, CloudCompare admin