Kindle Paperwhite goes to table of contents when switching books
 

Sometimes I read more than one book at a time. But the problem is that when I read book A, then read book B, when I go back to book A instead of going back to where I was reading, it goes to the table of contents

Sometimes, I never remember how, I either go forward and back (or back and forward) and it goes back to where it was. But sometimes it just goes back to the start of the book or if I accidentally click on a link to wherever I clicked.

This is starting to get annoying. Am really not liking my Paperwhite at all, it seems such a step backward from my deceased Kindle Keyboard 3

Do you bookmark where you stop?

I have an ageing PW2, currently running firmware version 5.9.6.1. I switch between reading several different books frequently and don't think I've ever had this happen. It always opens my books back where I left off (by pressing the home button in the upper left corner).

All of my books are side loaded AZW3s if that matters.

I have no idea how to bookmark, so I just exit.

And since I've copied most my library from my old Kindle Keyboard, most of it's mobis (a lot of them from here), not azw3

Read the user guide (you'll find it in your library). Seriously, it's full of useful information.

To add a bookmark, just tap the top right corner of the page.

Apparently not in this case, as leaving a bookmark still doesn't help. It still goes back to the TOC (and then the beginning).

Thank you though.

The solution seems to be to convert my mobis to azw3s

But now you have a bookmark, you can easily jump to it, so you've not permanently lost your place.

Have you restarted your kindle lately? Often, when little glitches like this start happening, a restart will fix the problem.

it is more likely to be an issue with your books, than with your device.
One test would be to grab some free samples of books from amazon and see if you can reproduce the problem with any of those books
then test with any complete book that you previously bought from amazon, but test by re-downloading it from amazon , not by copying it from some backup or other device....
if you can make it happen with a purchased book or a sample from amazon, then call them . you may get a free replacement device if yours is still under warranty