Hi jonholiday, your desktop Firefox should already be identifying itself as a desktop browser, so usually there's not much to be done.

Some sites have a "responsive" layout that automatically switches to mobile layout if you narrow the window or zoom into the page to make the text/images larger. To try to get a desktop layout, make sure the window is as wide as possible and "zoom out" by holding down the Command key and tapping the - key once or twice. Does the layout switch?

If the site previously set a cookie to always use mobile layout, you can clear the cookies and see whether that restores the default behavior. And the cache too, for good measure:

(1) Clear Firefox's Cache

See: How to clear the Firefox cache

If you have a large hard drive, this might take a few minutes. If you do not see the number going down on the page, you can reload it using Command+r to check progress.

(2) Remove the site's cookies (save any pending work first). While viewing a page on the site, try either:

• right-click (on Mac Ctrl+click) a blank area of the page and choose View Page Info > Security > "View Cookies"
• (menu bar) Tools > Page Info > Security > "View Cookies"
• click the padlock or "i" icon in the address bar, then the ">" button, then More Information, and finally the "View Cookies" button

In the dialog that opens, the current site should be pre-filled in the search box at the top of the dialog so you can remove that site's cookies individually.

Then try reloading the page. Does that help?

If none of the above helps and there's just one particular blog that has the problem, do you want to post a link to it?

A couple other notes:

(1) Firefox on MacOS X 10.6.x

You can't update to Firefox 50.1.0, but you could consider using the Extended Support Release of Firefox 45 to be more current with security fixes. More info in this article: Firefox support has ended for Mac OS X 10.6, 10.7 and 10.8.

(2) Questionable Extensions?

Your add-on data shows two that I am not sure you want:

• Email 4.0.12 (@Email) -- what is this?
• FromDocToPDF 7.103.10.39524 (_65Members_@download.fromdoctopdf.com) - some users have complained it took over their home page

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

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

In the left column, click Extensions. Then cast a critical eye over the list on the right side. All extensions are optional. If in doubt, disable.

Often a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step.

After that: How to set the home page