The reason why is when you switch to Unique mode, the folder structure for the saves changes.when I set it to unique my game save files no longer work...

There is a setting for each individual game for this right now.unique = creates separate save files for each user
shared = all users play with the same save file
So if you are fine with having one save for all users.. just use shared mode.
In future Loadiine versions, you will be able to choose the save mode for each game. (Not yet in the current release version)