At the end of the address box is a three-way Go, Stop, Reload control. While a page is loading, it should change to a red background with an X. Then change to a reload arrow once the page is loaded.

If you don't have that button, you can recover it using View > Toolbars > Customize. You also can move and split it back to the old style. (More detail on request!)

Thank you very much! I never noticed that change. Is there someplace in Firefox Helps that I should have looked to find this info? I apparently couldn't find the right words to search it out. Very frustrating! So I really appreciate being able to post a question!

I'm glad that helped. There are some "what's new" videos for Firefox 4, but I don't recall whether this is mentioned in there. If there isn't an overview article for the location bar, maybe someone should write one? Volunteers are always welcome.

It would be wonderful if someone would develop such an overview article, however, even better would be someone developing a glossary of terms that could be used in searching for information! More than half of my time is spent trying to figure out what word(s) to use that will direct me to the information I want! I can use a computer quite handily generally speaking, but I'm not so computer savvy that I know all the correct terminology, which appears to be very important. For instance "Location bar", while making sense now, never occurred to me to use as a search term. :-( Thank you again for your prompt, courteous help.

See:

• http://www.mozilla.com/firefox/features.html

Thank you, cor-el. I found that page after jscher referred to the "location bar". My only problem with that page is that two of the items mentioned there aren't available to me (I'm on Firefox Beta): 1) the Firefox Button and 2) the Bookmark Button. The web page indicates the Firefox Button is above the first Tab. Above my first tab is "File", "Edit", "view", etc., nothing else. And where the Bookmark Button is supposed to be is the "Feedback Button". So where else can I find these tools?

You see the orange (on Linux gray) Firefox button if the Menu Bar is hidden, so you need to hide the Menu bar via View > Toolbars, also accessible via Firefox > Options.
If you need to access the hidden Menu bar then press F10 or hold down the Alt key to make the Menu Bar appear temporarily.

Firefox 4 has two bookmark buttons with a star in the Customize window.
One star button has a drop marker that open a Bookmark menu.
The other star button without the drop marker opens the bookmarks in the sidebar.

You can drag the Bookmarks menu button with the drop marker in the Customize window from the toolbar palette on a toolbar (e.g. Navigation Toolbar or Tab Bar or to the left side of the Bookmarks Menu Items).
You only see the Bookmarks menu button if the menu bar is hidden.
If the bookmarks toolbar is visible then the default bookmarks menu button will appear on the right hand side of the Bookmarks Toolbar as part of the Bookmarks Toolbar Items.