Our friends at Yahoo changed how their toolbar works, making the configuration less flexible and taking over the new tab page. If you do not use the Yahoo toolbar, I suggest removing that add-on.

You can view, disable, and often remove unwanted or unknown extensions on the Add-ons page. Either:

• Ctrl+Shift+a (Mac: Command+Shift+a)
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Extensions. Then find Yahoo on the right side and take the action you prefer.

Some users are attempting to roll back to an earlier version of the toolbar; I haven't yet heard whether that works.

Disclaimer: I have no idea whether the following will allow customization. If you test it, please report back.

The previous versions of the "new" toolbar are available on the Add-ons site:

https://addons.mozilla.org/firefox/addon/yahoo-toolbar-and-new-tab/versions/

I don't know whether it will help, but you can turn off updating for the toolbar on the Add-ons page. Either:

• Ctrl+Shift+a (Mac: Command+Shift+a)
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Extensions. Find Yahoo toolbar on the right side and click the tiny More link under the title, then on that page, find the row for Automatic Updates and set it to Off.

Please post back with your experiences -- many other Yahoo users have the same concern.

For completeness, I should mention that there also are malware-ish add-ons that take over your new tab page and other functions. If you check the address bar for any unexpected Yahoo pages, do they contain a set of extra codes that might indicate it is an "affiliate" page?