Click on the down-arrow in a field type field to see available field types to convert to:
Change the field type of a field at any time! List Fields will attempt to convert the original content of the field to the new field type. If this conversion fails, you will be prompted a detailed Save Errors report.
The supported field types are:
If you have selected multiple documents, the field type change will be processed on all selected documents.
As soon as you press Enter, a new change log entry is created. Remember that List Fields doesn't process any changes unless you explicitly ask it to save the changes.
Press Esc to abort the field type change.