Thank you VERY much! I should have thought of an upgrade but it sounded so "scary". It is asking me to upgrade from Catalina 10.15.7 to BIg Sur which is 11 or 11.0.1. So I have do that before anything else. I had looked into Big Sur and it looks like some major changes which I am not excited about but will have to learn to love it.
As you say there must be an upgrade for the Kindle App but I can't deal with that till I have upgraded the MacBook.
I did find this on Wikipedia titled "MacOS Big Sur." I have put in one paragraph just to warn us all :
*** The rollout of Big Sur has been plagued with problems.[12] Upgrading to Big Sur has bricked some computers, rendering them unusable. Affected machines must be taken to Apple for repairs, since they cannot be rebooted and thus cannot be fixed via NVRAM, SMC, safe mode, or internet recovery. This problem mainly affects MacBook Pros from late 2013 and 2014, though some users have experienced similar problems with recent machines.[13][14][15] The initial rollout also disrupted Apple's app notarization process, causing slowdowns even on devices not running Big Sur ***
good luck to all! and thanks