I can’t update my apps it says to sign in because a previous charge I didn’t purchase

1.

Verify your payment information, you need to -> Sign in to your Apple ID account page and edit / update your Apple ID details -> https://appleid.apple.com                                                     

• On the Sidebar click Payment methods -> then tap Payments Methods and tap Manage payment method.

Or see -> Add a payment method to your Apple ID -> Add a payment method to your Apple ID – Apple Support (UK)

• If you want to change your card, you need to add first the new card, then remove the old card.
• or if you use your Apple Account balance, you need to set your Apple Account balance as your default payment.

If you update your payment method or add funds to your Apple Account balance, It would take about 1 to 3 business days in order to process.

If you're still unable to update your payment method, Contact Apple Support.

See also the following Apple articles:

Payment methods you can use with your Apple ID

Payment methods you can use with your Apple ID – Apple Support (UK)

fyi: Not all credit & debit cards seem to work with App Store / iTunes Store, try a different one, or preferably a credit card.

If your card is not accepted as a paymenf method, you need to contact your bank.

👉 If you can’t download or update apps on your iPhone or iPad

If you can’t download or update apps on your iPhone or iPad – Apple Support (UK)

scroll to point 2 & 3  ⤵️

Add a payment method

You may need to have a valid payment method on file, even if the app you want to download is free.

Add a payment method

Resolve a problem with your payment method

If your payment method has expired, declined or failed, or a message says "There is a Billing Problem with a Previous Purchase"

If your payment method is declined in the App Store or iTunes Store, see -> 

If your payment method is declined in the App Store or iTunes Store - Apple Support

⤵️

How to complete your purchase if a payment failed or was declined

1. On your iPhone or iPad, open the Settings app.
2. Tap your name.
3. Tap Payment & Shipping.
4. Add a different payment method and remove the old one. 
5. Try to complete your purchase.

If you still can't make a purchase

• You might have an unpaid order. Learn how to pay an unpaid order.
• Contact your financial institution. 
  • You might need to ask your financial institution to allow international purchases on your debit or credit card.
  • If you want to know why a debit card, credit card, or other payment method was declined, speak with your financial institution. Apple doesn't have information about why the payment method was declined.
• In some countries and regions, your payment method might be declined because of changes to local law. Learn about billing and purchases in Europe or what to do if your card is declined in India.
• Still need help? Contact Apple Support.

2.

. . . I didn’t purchase

Check for sure the following Apple articles:

View your purchase history for the App Store, iTunes Store, and other Apple media services

View your purchase history for the App Store, iTunes Store, and other Apple media services - Apple Support

How apps, content, and subscriptions from Apple are billed

How apps, content, and subscriptions from Apple are billed - Apple Support

If you see "apple.com/bill" on your billing statement

If you see "apple.com/bill" on your billing statement – Apple Support (UK)

• If you've checked reportaproblem.apple.com and your emailed receipts, and you're still not sure why you've been charged, contact Apple Support.

If you have followed all the steps and instructions and if you still need help, get support from Apple directly -> Get Support or call Apple in your region see -> Contact Apple for support and service or check -> here for more support and assistance.