What your asking isn't something FF does nor support that is only a 3rd party software or Addons do would do but then you must decide if they work. Your trying to push problems onto FF of which isn't FF a issue here.

Im am not trying to push the problem on FF.

Im asking FF and/or the community to work a solution for such issue.

I am certain there are plenty of users that travels a lot worldwide and would prefer to US $ set as main currency.

This is a end user forum help. What your asking the rest to do is find a program for your currency exchange and that isn't something we can do. You have to look online to find software or Smart phone app that can do the currency conversion that your asking for in real time. Currency exchange changes from min to min and what you saw 10 min ago will be different 10 min from now. Currency exchanges are in flux and never will be same from time to time. So you need to find a program or smart phone app that works for your situation.

I know exchange rates changes constantly hence why the interest in having a rates in USD and not local currency based upon geo-ip location.

I have searched for currency exchange add-ons with very limited success.

As I explained, I am sure im not the only one with this issue. Just thought it would be a topic to suggest as a future feature for FF by either turning off "reverse DNS look up" from X sites or have Y currency set as default preference for example.

https://addons.mozilla.org/en-US/firefox/extensions/ Copy/Paste Single keywords into the search | currency conversions

Windows 10 can open Settings and top enter Currency in the Search and change your Location. Change it back after you have finished.

To submit suggestions for new or changed features, may I suggest: Feedback: https://qsurvey.mozilla.com/s3/FirefoxInput/ or https://discourse.mozilla.org/c/add-ons

Please let us know if this solved your issue or if need further assistance.

If you primarily have this problem with the one site, ask them to stick with your last currency selection (it's probably stored in a cookie) rather than resetting it each time.

I did contacted the web site to report that users must entered each freaking time (after each search) the preferred currency since this issues started about a year and half ago and they are still trying to figure out where there arses are at yet.

So using the currency exchange page in Google after using those words does not help you I guess either. ?

Did you try the Extensions as I suggested as there were several that turned up in search. ?