You can update a saved skin by replacing its settings with your current storefront settings for template, color theme, custom colors and fonts, category page style, product page style, and any advanced CSS you've included.
When updating a saved skin, all of its settings are overwritten. To prevent permanently losing the skin's current settings, back them up with a different skin name before you overwrite the skin.
The settings for the skin are overwritten with the current settings of your storefront.
For additional information on Saved Skins in Quick Shopping Cart, see What are Saved Skins?