Main Blog Page Title is sticking and unchangeable

My main blog page title is sticking. This is the one seen in the margin of the browser and that appears at the top of the page source code. Normally, I should think, this should be able to be changed in the Settings/General pallet but when I do, this or when simply leave it blank the old title still keeps coming up in the source code for that page. Note that this does not occur in any other post or page than the one at https://myblogname/index.php. Information that I enter into the Site Title and Tagline fields of the Settings/General page end up in the Description field in the source code.

I’d assumed this was a problem with my theme. I tried subbing in various themes and the problem is independent of that. Where is that index.php drawing the out of date information from? Is there a coding bug that is bypassing the title field and dumping my title and description information together into the Description field of the source coding?

BTW, I’m pretty sure that I’m using version 3-point-something and for the life me can only find the message prompting me to upgrade to v 3.5.1 but not some indication of the version installed.

Peter