I have enchanting at 100% and have selected the extra perk that allows you to add second enchantment. But every time I go to enchant any of my objects it only shows me those that do not already have an enchantmet. What do I need to do so I can add second enchanment to swords, bows and armor.

Thanks

Isit even possible to change or add enchantmets on items that are already enchanted?

Afaik you can only add enchantments to an item once. So you can only add a second enchantment to unenchanted items.

You can only add two enchantments at once. You're not able to go back and re-enchant items.

Previously enchanted items are at their limit. As stated, you can only enchant fresh items.