Q: When I try to update my apps it says I need to update my payment method?

Then log into your iTunes account and update your payment method.

I had the same problem before. I used a prepaid gift card for purchasing apps and when I ran out of money it started asking me to update my payment method. Just go to iTunes or the app store and scroll down to the very bottom and look for your apple I.D. (below redeem and send gift) and go into it. After that a menu will pop up. Go to the first option,which is "view apple ID". It may ask you for your apple I.D. password. Next look for "payment information" (just below apple I.D.) and go into it. Next, there will be 4 choices of payment type; choose "none" as your payment method and it should be working normally. If that did not work, try buying an iTunes or Appstore card of any value ($15, $25, $50) and redeem it at the Appstore or iTunes store and it should make things normal. If that method didn't work, try downloading any app or song of any value (free or paid) after redeeming the iTunes/app store card.

Not all accounts have the option to select none. While it may be possible, if it isn't the method you describe for the gift cards is spot on.

to get the none option while selecting your payment method you have to try downloading a free app to get the none option

You might also want to look at this support document. There are more than one reason for this, and again, you cannot always find the none option. Why can’t I select None when I edit my Apple ID payment information? - Apple Support