Even though I’m trying to update apps it’s saying my payment method is not valid

When you have a card on an account it has to be valid and pass the iTunes validation irrespective of what you are trying to download. Try replacing it with a different, or see if you can remove (if your an remove you could also try re-entering its details from scratch) : Change or remove your Apple ID payment information in the iTunes Store - Apple Support

If you don't get the 'none' option on the payment details screen : Why can’t I select None when I edit my Apple ID payment information? - Apple Support