Understanding sync (the return)

Just getting started, so my questions are all fairly basic. I have done a sync, set the interval at five minutes, and when they pass, Joplin syncs the entire contents of my folders again.
My understanding is sync only is supposed to modify what’s been updated.
In the settings, I see I can only choose the destination of the sync (in my case, OneDrive), and the intervals.
What do I need to do to stop Joplin from going through all my notes every five minutes, and only update what’s been modified?

Joplin only syncs changed notes.