Presumably your version of Firefox is English and not Dutch ? If so I may have expected the User Interface to be English and also that it would by default select English versions of webpages.

The pref intl.accept_languages can include a comma separated list of languages to be accepted an on an English browser that may be en or at least include en

• see http://kb.mozillazine.org/About:config_entries#Intl.
  • & http://kb.mozillazine.org/About:config

So I do not know the answer to your question for certain but changing that pref to exclude NL may solve the problem. AboutConfig may be used to change prefs as explained in the article linked above. Type about:config into the location bar, and accept the warning. Then filter for the pref needed and right click to modify it.

I think there are addons that deal with this sort of thing and may be more convenient see for instance

• https://addons.mozilla.org/firefox/addon/locale-switcher/

As an aside

If you use Mozilla URLs without the locale they should default to either the en-US link or the link appropriate to the browser. Some pages will not be localised and some are only localised into a small number of languages.

Generic link Sync your Firefox bookmarks, history, passwords and more

• equivalent to https://support.mozilla.org/kb/how-to-update-to-the-new-firefox-sync (No Locale specified)
• en-US link https://support.mozilla.org/en-US/kb/how-to-update-to-the-new-firefox-sync
• Dutch Link https://support.mozilla.org/NL/kb/how-to-update-to-the-new-firefox-sync Bijwerken naar het nieuwe Firefox Sync

Look at the address in the address box. Do you see where it says; Mozilla.org/en-US/questions? When you land on the wrong language on Mozilla.org, just change the assress to read /en-US/.

Also, try this;

• Clear the Cache

Press the <Alt> or <F10> key to bring up the tool bar. Followed by; Windows; Tools > Options Linux; Edit > Preferences Mac; application name > Preferences Then Advanced > Network > Cached Web Content: Clear Now

and

• Remove Cookies

Press the <Alt> or <F10> key to bring up the tool bar. Followed by; Windows; Tools > Options Linux; Edit > Preferences Mac; application name > Preferences Then Privacy. Under History, select Firefox will Use Custom Settings. There is a button on the right side called Show Cookies.

Are you located in a Danish speaking country?

Where does your IP locate you?

• http://www.yougetsignal.com/tools/network-location/
• http://whatismyipaddress.com/

This issue can be caused by corrupted cookies or cookies that are blocked (check the permissions on the about:permissions page).

Clear the cache and cookies only from websites that cause problems.

"Clear the Cache":

• Firefox/Tools > Options > Advanced > Network > Cached Web Content: "Clear Now"

"Remove Cookies" from sites causing problems:

• Firefox/Tools > Options > Privacy > "Use custom settings for history" > Cookies: "Show Cookies"

Note, the Mozilla KB article up until; IIRC part way through last year; did use at least two cookies one for the browser version and one for the OS used; and the cookies were only set if you selected something other than the Verison or OS of the browser in use. It no longer does that using cookies.