When you sync files to OneDrive, you should work on the files that are created in the OneDrive folder on your computer. This is because the OneDrive sync app allows you to access and edit these files directly from your local machine, and any changes you make will be synchronized with your OneDrive in the cloud.
If you work on files in your original user file location (outside of the OneDrive folder), those changes will not be reflected in OneDrive unless you manually move or copy those files into the OneDrive folder. Therefore, for seamless syncing and access across devices, it is recommended to use the files in the OneDrive folder.