Hi Maurice,
If you have updated the setting 'Name indexing format' in EasySocial backend under settings -> users -> user search indexing, then you will actually need to purge the indexed data. To do this, go to your EasySocial backend under search indexer, click on the purge icon from the toolbar. Once your indexed data purged, you will need to re-index your users into the indexer. To re-index, click on the 'index item' icon from your toolbar.
Hope this help and have a nice day