Add/Modify custom Accept-Languages to Chrome/Firefox/IE for pseudolocalization testing

In Firefox

Use about:config

(There is a typo in qps-ploc in the screenshots, but you surely get the idea)

In Chrome

Edit the file C:\Users\USERNAME\AppData\Local\Google\Chrome\User Data\Default\Preferences, and add:

<code>{ ...

   "intl": {
      "accept_languages": "qps-ploc,en-us,en"
   },

   ...
}
</code>

For example: