Q: i wanna update my apps but i have this error ( there is a billing problem with previous purchase. please enter another payment method)

Until you have another payment method or can resolve the issue with the one you have, you will not be able to update your apps. Follow the Contact Us link at the bottom right of every page to find information on how to contact the iTunes Store Support team for assistance.

You will need to contact iTunes support to settle the past problem. Did you log into your account to see if it was something as simple as your credit card expiration date? That would prevent a charge from going through. See this link to contact iTunes Support. https://www.apple.com/emea/support/itunes/contact.html

See if you have an unpaid balance. Pay an unpaid balance in the iTunes Store - Apple Support

If you do, you can use many different ways to pay including and iTunes gift card. Payment methods you can use in the iTunes Store, App Store, and iBooks Store - Apple Support

-AJ