i need help fixing my app store to update apps

Read this document If a message says 'billing problem with previous purchase' or 'verification required' - Apple Support

You get a billing problem message because there is a problem paying for something a person bought in the past and this needs to be resolved before Apple will let you make a new purchase, even free items. It isn't a problem with a specific item, it's with the payment method used by you, or -in the case of Family Sharing- the Family Organizer..

Get the payment method owner to review their payment methods as in this document: 'Change, add, or remove Apple ID payment methods' on an Apple mobile device, a Mac, or a PC; click here --> Add a payment method to your Apple ID - Apple Support

- If the person is updating an old card and has ongoing subscriptions the person may need to first add the new card and make it the primary payment method before deleting the old card.

Related documents:

If the payment method is declined in the App Store or iTunes Store, click here --> If your payment method is declined in the App Store or iTunes Store - Apple Support

"There is a billing problem with a previous purchase." = "you have an unpaid balance in the App Store or iTunes Store"

- 'If you can't remove your last payment method or use no payment method with your Apple ID' click here --> Remove a payment method from your Apple ID - Apple Support

If none of the self-help solutions resolve your situation then ask Apple for help. Click here --> Choose your country or region - Official Apple Support Select your country, then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.

or:

Contact Apple for support and service --> "See a list of Apple phone numbers around the world." - Contact Apple for support and service - Apple Support