I am wary of using kindle for pc as it may make me unable to convertīut dont understand why an older version is refusing to let me sign in after uprading pc

I have been known to buy a book twice by accident, as find that covers and titles change such a lot.For the same book! I like to convert and save my books in calibreĪs it helps me know which I have bought before and read. There is even a more functional Kindle app available from the Microsoft Store for Windows 11 that is equivalent to Kindle for Android. If you just want to read on your PC and not convert you can use a newer version of Kindle for PC instead. Assuming that you own a Kindle and not a Fire tablet then that downloaded copy can be used for converting in calibre, assuming that is your intent. If so that download will usually be locked to that particular device using DRM. If you are downloading copies using the Download & Transfer function of Amazon's website then you must have selected a Kindle device or Fire tablet as the intended destination.

The Kindle app cannot download books unless it is signed in. The thread Dealing with Kindle for PC/Mac 1.19 and KFX in calibre has information about workable versions of Kindle for PC and other alternatives for downloading Kindle books.