You'd need to take this up with your bank - Amazon and other retailer's payment systems only ever request additional verification on instruction from your bank.
If you don't want to do that, the only option you have is to buy an Amazon gift card, add it to your account and use its balance to pay for any ebooks - by default any purchases made from your Kindle will automatically be charged to your gift card balance.
For 10 years, I have downloaded books onto my kindle.
Now it says my bank wants to verify payment.
What does this mean? Why is it doing it? How can I return to what I had?
I cannot, get out of bed, go to my study, fire up my PC and pay for a book, everytime I want to download a book onto my kindle.
Even the email I've received, doesn't actually say how I am supposed to do this even if it wanted to. Which I don't.
The clue is in the question. As you say, your BANK wants to confirm and approve payments.
I know that Santandar and NatWest have added web security steps - neither of which worked well (for me) with Amazon spending until I went though their security system - everything then went back to normal for one-click payments.
It may be worth your while contacting your bank/card service and seeing what needs to happen. I can only speak from personal experience but I had a problem and then it went away.
Rollback Post to RevisionRollBack
I wonder why someone would follow their own alternative forum profile.
Has the card you've got on your account expired? Does your payment method need updating? Check that on your account first.
You said the email your received doesn't even tell you how to ...... have you considered it might be a scam/phishing email ... ie claiming to be from your bank or Amazon (you haven't said from whom) ... did it have a link to click on to take you anywhere? If so, did you click on it cos if you did, I'd suggest you immediately change your online banking and your Amazon password. If you don't do online banking, phone your bank and tell them you clicked on a link on an email you got which appeared to be from them but may not have been.
If you didn't click on the link ..... just delete the email .... and separately login either your online banking and Amazon account and change your password.
OR are you saying that you got the message when you tried to download a book from the Amazon website, before you also got an email.
In that case and it was genuinely Amazon asking you to verify first, as people have said, that's a bank requirement, not Amazon's. Banks randomly carry out verification checks and you've just been selected this time. Often the verification request happens instantly on the same device and just asks you to input requested characters from your banking pin number or password. If you get them right, the transaction is confirmed, the book downloads and you probably won't be selected for verification again for a long time.
So you don't necessarily have to get out of bed, go to your study, fire up your PC and pay for a book IF it asks you for those details on the device you're on ... and IF you can remember those details correctly. Otherwise, you will .... but probably only the first time it asks for verification.