The latest version of Mozilla's web browser is looking to unseat Microsoft Edge as the default browser in Windows 10.

Watch out, Microsoft. Firefox is gunning for its own chunk of the browser space in Windows 10.

Released on Tuesday, Firefox 40 is the latest version of Mozilla's browser and the first designed with Windows 10 in mind yet with its own look and feel. The icons sport greater contrast to better stand out. The screen opens up more real estate for the actual web pages. And a minor renovation paints the top and bottom areas of the browser a more user-friendly gray instead of the standard white.

But it's Firefox's move to assert itself as the default browser that stands out the most in an attempt to challenge Microsoft. In July, Mozilla CEO Chris Beard lashed out at Microsoft for not only making its new Edge browser the default in Windows 10 but also for making it difficult to switch the default to a different browser. In an open letter to Microsoft CEO Satya Nadella, Beard called the software giant's action an "aggressive move to override user choice."

Mozilla needs all the help in can get in rounding up more users. Firefox is stuck at a distant third in terms of browser market share, according to Web tracker Net Applications. In July, Microsoft's Internet Explorer was top dog with a browser traffic share of 53 percent, followed by Google Chome with 27 percent. Firefox, which at one point was ahead of Chrome, came in third at just 12 percent, Net Applications reported. Now with its new version of Firefox, Mozilla is fighting Microsoft for a slice of Windows 10 territory.

As usual, Firefox asks if you want to set it as the default browser the first time you launch it. You can say 'yes,' 'no,' or tell Firefox to ask you the same question each time. No matter how you answer that question, you can change the default any time you want, but the process is more cumbersome in Windows 10 than it was in previous versions of Windows.

Normally, you would open Firefox, click the toolbar icon with the three horizonal lines (known as a hamburger menu). From there, you'd click on the Options icon and under Startup, click the button to make Firefox your default browser. In Windows 8.1 and previous versions, that would do the trick.

But in Windows 10, you have to go a step further. In the new OS, Microsoft now takes you to a system setting that still shows Edge as the default browser. You have to click on that setting and change it to Firefox. You can also just bypass the steps in Firefox and go directly to the Windows 10 Settings page, as described in this CNET how-to article.

Still, the whole procedure is unnecessarily confusing, mostly because it's different than in prior versions of Windows. That's why Mozilla made sure to post a support blog page to tell you just how to switch the default to Firefox.

With version 40, Firefox also now wants to be the goto browser for your web searches. Normally, when you run a Web search from the Windows 10 taskbar search field, Microsoft Edge pops up to reveal the results using Microsoft Bing. But now if you set Firefox as the default, Firefox takes over to show you your search results using the search engine of your choice. The first time you try this, Windows 10 will ask if you want to use Firefox every time. Just answer yes, and it will become your default browser for all web searches from the taskbar search field.

There's one more change in the new version of Firefox aimed toward beefing up security. Browser add-ons can sometimes be a source of malware, most notably those that aren't certified. An add-on can be a colorful theme, an extension such as an ad blocker, or another piece of software that enhances the browser in some way. To make sure an add-on is secure, a team of people at Mozilla check each add-on and approve, or certify, the ones that are safe to install.

Starting with Firefox 40, Mozilla will now certify all add-ons that you attempt to install. For now, the browser will simply warn you if the add-on is uncertified, or unsigned. But in future releases, Firefox will actually disable any add-ons that are not signed.

The move to disable unsigned add-ons may trigger some complaints from Firefox users who like to beef up their browser with add-ons. Mozilla said it's working with add-on developers to help them meet the new standards. But that process is likely to take time. So users of future Firefox versions may find themselves unable to install a favorite add-on until and unless it's been certified by Mozilla.