Thank you for reaching out on the community and telling us about your issue. To clear things up here for you your data file and sync are two different things. Your data file is stored only locally to your computer (Or a place you choose to store it).
The sync is an add on to the file. Its purpose is to communicate with your file on your computer and mobile devices. It communicates with your devices in order to sync to your main file located on your computer. This is an optional feature than can be turned on and off if you would like to try it. Here's also an additional article that has a bit more information if you'd like to know more.
Hope this helps out!
... Your data is stored in your ".QFD" file which always resides in on your computer's hard drive ...