In Behaviour, under the reports tab, you can specify the File Name Prefix. As per the (now updated) documentation, the name can be an expression. However, there is a bug in the filename generated. When I use a column name, it does not appear in the name of the file when the report is generated.
When I test the expression CONCATENATE ( “SomeName_”, [ColumnName] ), the [ColumnName] appears in the test expression. But it does not appear in the report name when the report is generated. See video below:
