Please read what a Tab is. https://en.wikipedia.org/wiki/Tab_%28GUI%29

Are you mistaking "Tab" for "bookmark"? https://support.mozilla.org/en-US/kb/create-bookmarks-save-your-favorite-webpages

Thanks the-edmeister for your response. Yes, I realize that what I thought were tabs are actually bookmarks and I figured out what I was doing without having to read the articles. (I'd inadvertently enlarged the entire page which enlarged the bookmarks and caused them to populate at; 3 across instead of the 5 that I'd had previously.)

However, my other question then would be why aren't certain websites like Netflix not automatically bookmarked as most others are? I understand about security issues which prevent the addition of some websites, but aside from my email provider, it's difficult to fathom why Mozilla wouldn't support Netflix.

Thanks for responding, Kat

If you aren't going to read the KB articles that you are referred to you 're wasting my time.

Firefox doesn't "automatically" bookmark any webpages. And page zoom doesn't affect the Bookmarks Toolbar which will hold many more than just 3 to 5 bookmarks.

It now sounds like to are referring to the new Tab page which displays recent and frequently visited websites. The new Tab page typically has 3 to 5 columns of tiles (and 2 or 3 rows of tiles); the number depends upon the width (and height) of your monitor and the saved zoom setting for the new Tab page. https://support.mozilla.org/en-US/kb/about-tiles-new-tab

https://support.mozilla.org/en-US/kb/customize-new-tab-page

https://support.mozilla.org/en-US/kb/thumbnails-new-tab-page-missing-how-get-them-back

Excuse me for wasting your time. Since I'd already figured out what was causing the tab/bookmark problem AND RESOLVED IT MYSELF there was no reason to waste MY time reading the articles.