Firefox doesn't think that you're anywhere (unless you've turned on 'location sharing'). Services like Google though use both your IP address and your search history to try to workout where you are.
For example, somebody asked a question here about car hire in Dublin, resulting in me searching for relevant companies. The following day I noticed that all my 'shopping' searches in Google were returning prices in euros and suggesting sellers in Ireland (even though I'm in Suffolk).
If it's only Google that thinks you're in New York, carry out a search for something, scroll down to the bottom of the page and click on 'Use precise location' to correct the problem.
Alternatively, simply clear your browser's history, so that Google doesn't recognise you as the person who was, say, searching for information about Broadway theatres. (Click the three lines, top right. Then on 'Options', 'Privacy & Security' and 'Clear All Current History').
If it's something else that thinks you're in New York, check that your internet traffic isn't being routed via a US proxy server by seeing how your IP address is shown here:
https://whatismyipaddress.com/