Display formats for columns
When you need to change default format for columns, you should implement additional settings.
For Webforms use Appearance.AttrElementFormat property of QueryColumnsPanel control. By default, it's set to {entity} {attr} value what means that we need to show the entity name and then attribute's name. You can set it to simply {attr} to remove the entity name part.
Additionally, you may also want to change the format of the first (Expression) column in Columns Panel - use EntityAttrExpr.TextFormat static property for that.
So, combining both these options, here is the code sample:
QueryColumnsPanel1.Appearance.AttrElementFormat = "{attr}";
EntityAttrExpr.TextFormat = "{attr}";