I can't open old version excel 97-2003 file by program excel 365

Hi chuntinyam please follow the steps in the link below to solve the issues https://support.microsoft.com/en-us/office/save-an-excel-workbook-for-compatibility-with-earlier-versions-of-excel-169a0336-965b-4430-8554-4e7b5db79947 I hope this helps.