The import filters of a folder contain the column assignments related to a data source. Available Data sources:

• a data source selected during import (text file, ODBC-source, ....)
• or the own folder, if records are copied within the folder.

Delete import filter: If you delete an import filter, this is re-established with the next import from the same data source again.

Show column assignment dialog with next import: If the import filter is already known for a data source, the column assignment dialog is not shown during a import from this data source anymore. It is used therefore the known column assignment.
If you want to change the column assignment afterwards, you have to activate this option.