If there is a need to change the type of column after items have been added to an iSheet, first create an entirely new column with the correct column type. Then move the data from the old column into the new column. Depending on the type of data and number of rows, this can be done by manually re-entering the data, or by using the import process to copy the data into the
Import template
and for import into the iSheet in bulk. Only, then after the data has been copied and brought back into the iSheet should the old column be deleted.