I downloaded and installed the latest Nitro Pro version, 12.12.1.522. So far it's not crashing / shutting down after I edit a text box, so there's that. If it starts happening again, I'll check back in here.
>>>> However, the bug where "every time I click on the text box to make a change, ALL the lines in the text box move closer together" is still happening.
>>>> One suggestion: it would be nice if Nitro Pro had a "check to see if there is a newer version available" button in the "About Nitro Pro" dialog box. It would be certainly more useful than the "Legal Notices" or "Deactivate" buttons current there ....