And for your second question this is what I believe:
When we start, restart or exit NVDA, our focus doesn't remain where we kept it.
This is how I switch screenreaders:
1. Exit the first screenreader. In your case, exit NVDA.
2. open start window by pressing window key.
3. Type the name of the screenreader which you want to start. In your case you can type JAWS and press enter.
Sometimes, searching in the start window doesn't yield expected results. So I use run
dialog box . To open Run
dialog box one can press Windows+R. But to start any program from the run dialog box, we have to type the full name. for NVDA it isNVDA and for JAWS it is JASW+version like JAWS2024 or something. I think, with enough practice, one don't need any screen reader to go to run
dialog box or start any screenreader from the start window.
Thanks.