By 'create a datasheet' you mean you have built a form? The form has a RecordSource? The comboboxes are bound to fields of the RecordSource? The advice given in the other thread applies to your situation. You must bind this control to competitor_ID field of form's RecordSource. You want to save the competitor ID, not the actual name. The combobox should be multi-column. Review tutorials at
http://datapigtechnologies.com/AccessMain.htm especially the ones about comboboxes in the section AccessForms:ControlBasics.