If I add a new colour later, will I lose the prices I already entered for my variants?

No. When you add a value, Wcart keeps every row you have already filled in and only adds rows for the new combinations.

1. Open the product and go to the Variants card.
2. In the colour option, type the new value, for example Green, and press Enter.
3. New rows appear for the new combinations, such as "S / Green". Fill in their Price, Qty and SKU.
4. Click Save.

Be careful when removing a value, for example clicking × on "Red". This removes every variant row that uses it, including their prices and stock. Renaming an option, for example Color to Colour, also clears the price, stock and SKU on every row, so avoid renaming once the table is filled in.