You did say what you have tried, so . . . .

Type about:addons<enter> in the address bar to open your Add-ons Manager. Hot key; <Control>(Mac:<Command>)<Shift> A)

In the Add-ons Manager, on the left, select Extensions. Remove Yahoo Anything. Now do the same in the computers Programs Folder.

Windows: Start > Control Panel > Uninstall Programs. Mac: Open the "Applications" folder. Linux: Check your user manual.

You may have ad / mal-ware. Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.

After the problem is fixed, Bookmark and use this; Download the Mozilla Search Reset {web link} This add-on is very simple: on installation, it backs up and then resets your search preferences and home page to their default values, and then uninstalls itself. This affects the search bar, URL bar searches, and the home page.

Separate Issue; Your System Details shows;

Installed Plug-ins

Adobe PDF Plug-In For Firefox and Netscape 11.0.13 Adobe PDF Plug-In For Firefox and Netscape 10.1.16
Having more than one version of a program may cause issues. You must remove the older programs. Then get the current full installer.

Adobe PDF Plug-In For Firefox and Netscape: Adobe Reader Version 2015.009.20069 Note: McAfee Security is offered in the download.

What is the full URL of the unwanted home page? Often there is an indication in the URL of the culprit.

You could check or update your home page address using the Options page: Startup, home page, tabs, and download settings.

If there's nothing strange about your home page address or you want advice on the URL, you can copy/paste it into a reply.

Or if the problem ONLY occurs when using your Firefox desktop shortcut or pinned taskbar icon, and doesn't occur when you use either of these --

• Ctrl+n to launch a new window
• click the Home button on the toolbar

-- then please check for a hijacked 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.

The Target line should not have anything after this part:

• 64-bit Windows, standard 32-bit Firefox: "C:\Program Files (x86)\Mozilla Firefox\firefox.exe"
• 64-bit Windows, test 64-bit Firefox: "C:\Program Files\Mozilla Firefox\firefox.exe"
• 32-bit Windows: "C:\Program Files\Mozilla Firefox\firefox.exe"

If any URLs are listed after that, clear them out and save your change. To test, you can either:

• Desktop shortcut: double-click the icon to launch a new window
• Pinned taskbar icon: right-click the icon, click Mozilla Firefox to launch a new window

If you only get your home page, it worked. You probably need to do the same for your other browsers.