Auto-sync
What it does
Once a source is connected, the widget keeps its reviews current without anyone doing anything. New reviews appear, your rating and count follow the source.
How it works
This applies to the 56 sources collected from a link. The fifteen manual sources are exactly that — reviews you entered, which stay as entered until you change them.
The rating and review count in the header always come from the source rather than being calculated in the widget, so they stay accurate regardless of what you filter.
The thing people get wrong
People reinstall the embed code expecting it to refresh something. The code is just a pointer; the reviews are fetched behind it and reinstalling changes nothing.
What it does not do
If a review has not appeared after a few days, the cause is usually a filter or the sort order rather than the sync. What to check.