Variation based products in Sellbrite all contain variation values, such as "small", "red", "cotton", "medium", "blue", etc. If you would like to change any of these variation values to something other than what you currently have, you are going to want to follow these 3 steps...
1) Export your Products using the "All Data" CSV export.
2) In your Product CSV, change the variation values in the respective variation cells.
3) Import your adjusted and saved Product CSV back into Sellbrite and see that your variation values have changed.