function update() {
const book = SpreadsheetApp.getActive();
const sheet = book.getSheetByName('Пример');
sheet.getRange('A2:A')
.setValues(sheet.getRange('A2:C').getValues()
.map(([kladovshik, _, externalSource]) =>
[externalSource === 'Продан' ? externalSource : kladovshik]));
}