Showing sample or wrong reviews
The short answer
Sample reviews mean no source is connected yet — every widget ships with placeholder reviews so you can see what it looks like. They disappear as soon as you add your own.
Reviews from the wrong business mean the wrong source is connected, usually a similarly named place.
Sample reviews
These appear when a widget was created but never configured. The most common route is creating the widget through a marketplace — the Wix App Market, for instance — without then creating an Elfsight account and connecting a source. Log in, connect your source, and they are replaced automatically.
Reviews from a different business
The source that got connected is not yours. It happens most with Google, where a business-name search can match a similarly named place in another town.
Remove the source and re-add it, using the business name together with the address, or your Place ID, which is unambiguous.
Neither of those
If reviews are real but not the ones you expect, check filters and sorting before assuming the source is wrong.