PreProduct piggybacks off of existing Shopify products, so changing details will mostly happen in the same place via Shopify.
Navigate to Shopify dashboard > Products dashboard > then find the product you would like to change. Make the change to the product/variant whether this is a title change, description change etc.
Now open PreProduct and select your listing from the main dashboard and on the left hand-side click the button “Re-sync with Shopify”. PreProduct will then reflect the new details/changes.