I'm not sure where the problem is. Possibly your home page has been changed? You can use the steps in this article to reset your home page: How to set the home page.

Some reasons that setting might not solve the problem:

(1) An Add-on is replacing your home page with a different one, or a different startup page.

(2) The shortcut you use to start Firefox has been hacked to point Firefox to a different start page.

(3) Firefox is attempting a crash recovery at startup, re-opening old tabs or showing a list of old tabs.

For #1:

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
• type or paste about:addons in the address bar and press Enter/Return

In the left column of the Add-ons page, click Extensions. Then cast a critical eye over the list on the right side. Any system extensions that Firefox installs on its own are hidden from this page, so everything listed here is your choice (and your responsibility) to manage. Anything suspicious? If in doubt, disable.

Sometimes a link will appear above a disabled extension to restart Firefox before the change takes effect. You can complete your work on the tab and click one of the links as the last step.

Any improvement?

For #2:

The Firefox icon can be set up to launch specific pages at startup (or more specifically, when you use the icon). To check whether that is set:

First, open the shortcut as follows:

• Desktop shortcut: right-click the icon, choose Properties
• Pinned taskbar icon: right-click the icon, right-click Mozilla Firefox, choose Properties

Windows normally will select the Shortcut tab. If not, go ahead and click the Shortcut tab.

You'll see the Target highlighted. On Windows, that usually is no more and no less than the following, depending on 32-bit vs. 64-bit:

• "C:\Program Files\Mozilla Firefox\firefox.exe"
• "C:\Program Files (x86)\Mozilla Firefox\firefox.exe"

If anything follows after that, try clearing it out.

After OK'ing the Properties dialog, you can test right away to confirm that Firefox now launches only your home page. Either:

• double-click desktop shortcut
• right-click pinned taskbar icon, click Mozilla Firefox

Success?

For #3:

Let us know if you think that is the problem.

Can you attach a screenshot?

• https://support.mozilla.org/en-US/kb/how-do-i-create-screenshot-my-problem
• use a compressed image type like PNG or JPG to save the screenshot