You can download your form/project as XLSForm, do the type change in Excel and then re-import the changed form in the same project.
You may do a check of your form with the online validator before the re-import.
You can download your form/project as XLSForm, do the type change in Excel and then re-import the changed form in the same project.
You may do a check of your form with the online validator before the re-import.