By default the Close buttons appear on all tabs.

1. Type about:config into the address bar and press Enter.
2. Press the big button to bypass the warning.
3. In the search bar, paste browser.tabs.closeButtons
4. In the search results, double-click browser.tabs.closeButtons and set its value to 1

• http://kb.mozillazine.org/Browser.tabs.closeButtons

If you want to hide the Close button on inactive tabs and show it only on mouseover,
1. Install the Stylish add-on.

• https://addons.mozilla.org/firefox/addon/stylish/

2. Open the Add-ons Manager, User Styles category and click the Write a New Style link at the top.
3. Paste the following in the style editor box and click the Save button.

@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);

.tabbrowser-tab:not([selected]) .tab-close-button {
  visibility: hidden !important
}

.tabbrowser-tab:not([selected]):hover .tab-close-button {
  visibility: visible !important
}

If I'm not mistaken, this is also an option in the Tab Mix Plus add-on.

• https://addons.mozilla.org/firefox/addon/tab-mix-plus/

Note that Firefox hides the close button on inactive tabs if there are enough tabs open to make them shrunk below a specific minimum.

• http://kb.mozillazine.org/browser.tabs.tabClipWidth

You could try right-clicking which gives you a menu that lists a 'close tab' option.

The easiest way to close a tab is to middle-click the tab with the mouse scroll wheel.

Thanks for all your help, everyone!

In about:config change the value of browser.tabs.tabClipWidth to 50.

You said by default the close button appears on all tabs. Well, now it doesn't. It's been moved to one singular close button on the right that does nothing but slow the work process down.

How do I get a close button to appear on each tab again?

Sounds that the browser.tabs.closeButtons pref has been changed to 3, see:

• http://kb.mozillazine.org/browser.tabs.closeButtons

Thank you for your reply.

However, I did the about:config thing, and the value for Browser.tabs.closeButtons was already set on 1, which is the default, which should display a button on each tab. I've enclosed a screen shot.

I don't know why this went sideways. FF asked for an update a couple of nights ago, so I let it do the update and then shut it down, because I was done for the night. When I turned it on the next day, that's when the problem appeared, and I hate this browser more and more every day it stays this way.

What else can I try?

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Firefox/Tools > Add-ons > Appearance).

• Do NOT click the Reset button on the Safe Mode start window.

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Thank you so much for showing me how to troubleshoot this.

The problem was the "Hide Tab Bar With One Tab 1.2beta" extension. I disabled that, but now I have that annoying single tab when it's the only one open.

Is there a way to resolve that, please?

Install the latest update (beta 3) of the extension.

• https://addons.mozilla.org/firefox/addon/hide-tab-bar-with-one-tab/

You are an absolute genius! Everything is working perfectly again. Thank you so much for all your time today!

I'm back in love with FireFox!

You're welcome.