There is a hidden setting for new tabs...

(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the search box above the list, type or paste newtab and pause while the list is filtered

(3) Double-click the browser.newtab.url preference and enter your preferred page:

• Page thumbnails (default) => about:newtab
• Blank tab => about:blank
• Built-in Firefox home page => about:home
• Any other page => full URL to the page

Note: when changing it to Google, use a complete ultimate URL such as https://www.google.com/ -- if you use a partial URL, there will be a brief delay while Google redirects Firefox to that ultimate URL.

Press Ctrl+t to open a new tab and verify that it worked. Fixed?

Two gotchas:

• If Firefox ignores the setting, one of your extensions may be overriding it. You can review, disable, and/or remove extensions on the add-ons page:
  
  Tools menu > Add-ons > in the left column click Extensions

• If the change works but at the next startup is back to Google, you might have a user.js file in your personal Firefox settings folder (your Firefox profile folder). This article describes how to track down and remove the file: How to fix preferences that won't save.

Any luck?

This might not be the same for everyone but I noticed that at the bottom of the search page I was trying to get rid of there was a link titled 'reset tab settings to normal' then I was prompted by a dialog window to change the default tab. this worked for me.

This worked perfectly. Thanks!