Style ID, Option Code, and Size values are not editable by spreadsheet
Brandboom uses these 3 attributes to identify the product to update. Therefore, any changes to these values will be recognized as being new, alternate values instead of a request to change an existing value.
For example, if you have a Size value of "S" and you change it to "Small" on your spreadsheet, Brandboom will not recognize your intent to change S→Small. It will treat "Small" as a new value, and if it doesn't already exist, it will add it to your product or create a new product.
If you need to modify any of these 3 attributes, you can do so manually in Brandboom or contact Support to assist you.